He held off compatriot Francesco Casagrande, who like Bugno was attempting to salvage something from an otherwise disastrous race. Third place fell to Russian Sergei Ouslamine. Russian Pavel Tonkov still leads overall by 20 seconds from Latvian Piotr Ugrumov.
Bugno, 32, with a string of past triumphs including the 1990 Giro and two world titles in successive years, started the stage 42 minutes 45 seconds behind Tonkov. His attack 50 kms from the finish was no threat to the Russian, but for Bugno it was a chance to silence the fickle Italian media.
His last Giro stage win came two years ago at Loreto Aprutino. That year he took the Tour of Flanders classic, and it was the end of a four-year spell of dominance in which he also won the World Cup series.
Team mates had said that Bugno was finding it hard this year to come to terms with the new era of successful Italian riders, and that his motivation was gone. Casagrande, one of the new Italian talents, was tipped for success in this Giro but, like Bugno, lost heavily in the mountains where he was expected to make an impact.
So when Bugno raced away, Casagrande was soon with him, as were Ouslamine, Russian Alexei Sivakov, Spain's Manuel Beltran and Bugno's team mate Carlo Finco of Italy. Their lead of more than one and a half minutes dipped momentarily as the main field stepped up the pursuit through the Aosta valley, where terraces of vineyards are perched high above the road leading to Mont Blanc and the Swiss border.
Then in the final 10 kms the course rose rapidly and Bugno, in his tricolour jersey of Italian number one, reached the finish two minutes 46 seconds clear of his pursuers.
Monday's 180-km 16th stage takes the riders from Aosta into Switzerland for a finish in Lausanne, home of the Olympic organisation, just over two weeks since the Giro set off from the site of the first modern Games in Athens. Bugno's success followed the victory of his Swiss team mate Pascal Richard at Briancon on Saturday.
Bugno said: "Because I am not good enough now for a top overall placing, I have to motivate myself for stage wins. "After all the problems I had in the mountains I wanted to win, and I did not want to disappoint my fans. I attacked today for them, and this win is theirs."
1. Gianni Bugno (Ita) MG-Technogym 5.48.06 2. Francesco Casagrande (Ita) Saeco s.t. 3. Sergej Oeslamin (Rus) Refin-Mobilvetta s.t. 4. Manuel Beltran Martinez (Spa) Mapei-GB s.t. 5. Alexei Sivakov (Rus) Roslotto-ZG s.t. 6. Carlo Finco (Ita) MG-Technogym + 0.03 7. Marco Milesi (Ita) Brescialat + 2.46 8. Mariano Piccoli (Ita) Brescialat s.t. 9. Claudio Chiappucci (Ita) Carrera + 2.52 10. Stefano Faustini (Ita) Aki-Gipiemme s.t. 11. Fabrizio Guidi (Ita) Scrigno-Blue Storm + 2.54 12. Giuseppe Calcaterra (Ita) Saeco 13. Glenn Magnusson (Swe) Amore e Vita 14. Daniele Contrini (Ita) Brescialat 15. Denis Zanette (Ita) Aki-Gipiemme 16. Marco Vergnani (Ita) Amore e Vita 17. Marco Velo (Ita) Brescialat 18. Abraham Olano (Spa) Mapei-GB 19. Marco Artunghi (Ita) Carrera 20. Andrea Noe (Ita) Mapei-GB all s.t. 21. Loda 22. Kjaergaard 23. Zaina 24. Abdujaparov 25. Tonkov 26. Zen 27. Pulnikov 28. Rebellin 29. Spruch 30. Gotti 31. Faresin 32. Uria; 33. Serpellini 34. Robin 35. Cenghialta 36. Ugrumov 37. Baldinger 38. Patuelli 39. Berzin 40. Shefer 41. Rodrigues Quintino 42. Buenahora 43. Jaskula 44. Laddomada 45. Bo Larsen 46. Bontempi 47. Cattai 48. Checchin 49. Totschnig 50. Richard 51. Saligari 52. Herve 53. Roux 54. Puttini 55. Guerini 56. Donati 57. Baffi 58. Petilleau 59. Lombardi 60. Casarotto 61. Cipollini 62. Furlan 63. Belli 64. Fernandez Gines 65. Bettin 66. Boscardin 67. Conti 68. Scirea 69. Vatteroni 70. Roncacio Gonzalez 71. Manzoni 72. Pelliconi 73. Salvato 74. Pellicioli 75. Rodriguez Nelson 76. Garcia Ignacio 77. Missaglia 78. Frigo 79. Garcia Felix 80. Vidal 81. Bramati 82. Simeoni 83. Tronca 84. Hodge 85. Konyshev 86. Andriotto 87. Lanfranchi 88. Johnsen 89. Zberg 90. Laukka 91. Di Grande 92. Djavanian 93. Cauz 94. Perona 95. Dotti 96. Cerezo 97. Gianetti 98. Vona 99. Colombo 100. Caruso 101. Imboden 102. Della Vedova 103. Sanchez De La Rocha 104. Galletti 105. Moller 106. Gorini 107. Piepoli 108. Petito 109. Teteriuk 110. Barbero 111. Casagranda 112. Sierra Pena 113. Forconi 114. Brognara 115. Ouchakov 116. Brignoli 117. Gontchenkov 118. Massi 119. Casagrande Filippo 120. Gasperoni 121. Coppolillo + 3.33 122. Davidenko + 11.43 123. Crepaldi. Starters: 124 Finishers: 123 Abandon: 1 (number 59 Plaza).
1. Pavel Tonkov (Rus) Panaria-Vinavil 67.10.55 2. Piotr Ugrumov (Rus) Roslotto-ZG + 0.20 3. Enrico Zaina (Ita) Carrera + 0.38 4. Davide Rebellin (Ita) Team Polti + 0.44 5. Ivan Gotti (Ita) Gewiss + 1.14 6. Stefano Faustini (Ita) Aki-Gipiemme + 1.15 7. Abraham Olano (Spa) Mapei-GB + 1.27 8. Eugeni Berzin (Rus) Gewiss + 1.41 9. Hernan Buenahora (Col) Kelme-Artiach + 1.58 10. Claudio Chiappucci (Ita) Carrera + 2.00 11. Alexander Chefer (Kaz) Scrigno-Blue Storm + 2.10 12. Jean-Cyril Robin (Fra) Festina + 2.43 13. Beat Zberg (Sch) Carrera + 2.51 14. Pascal Richard (Sch) MG-Technogym + 2.59 15. Bruno Cenghialta (Ita) Gewiss + 3.27 16. Pascal Herve (Fra) Festina + 3.41 17. Georg Totschnig (Aut) Team Polti + 4.33 18. Michele Laddomada (Ita) Amore e Vita + 5.28 19. Fausto Dotti (Ita) Brescialat + 5.34 20. Vladimir Pulnikov (Ukr) TVM + 6.05 21. Fernandez Gines + 6.54 22. Belli + 6.58 23. Teteriuk + 7.43; 24. Laukka + 8.13 25. Garcia Felix + 10.40 26. Zen + 11.12 27. Lanfranchi + 11.18 28. Faresin + 12.12 29. Di Grande + 12.42 30. Guerini + 13.09 31. Finco + 13.55 32. Gontchenkov + 15.35 33. Rodriguez Nelson + 17.19 34. Jaskula + 18.27 35. Cattai + 20.44 36. Casagrande Franc. + 20.56 37. Pellicioli + 21.44 38. Beltran + 24.21 39. Massi + 25.59 40. Vergnani + 27.42 41. Noe + 30.26 42. Tronca + 31.58 43. Piepoli + 32.54 44. Bo Larsen + 36.23 45. Donati + 36.54 46. Roux + 37.09 47. Spruch + 38.04 48. Uslamine + 38.17 49. Puttini + 39.01 50. Bugno + 39.39 51. Furlan + 40.43 52. Checchin + 41.37 53. Piccoli + 42.33 54. Della Vedova + 43.20 55. Petilleau + 43.51 56. Vona + 43.58 57. Roncacio Gonzalez + 46.32 58. Patuelli + 47.50 59. Barbero + 49.19 60. Gasperoni + 50.04 61. Gianetti + 50.07 62. Konyshev + 55.27 63. Bontempi + 57.01 64. Petito + 58.04 65. Guidi + 59.55 66. Loda + 1.02.11 67. Garcia Ignacio + 1.02.15 68. Sivakov + 1.02.22 69. Simeoni + 1.02.24 70. Caruso + 1.02.44 71. Sanchez De La Rocha+ 1.03.23 72. Bramati + 1.03.59 73. Missaglia + 1.04.03 74. Imboden + 1.04.59 75. Serpellini + 1.05.23 76. Galletti + 1.05.40 77. Saligari + 1.06.14 78. Bettin + 1.06.20 79. Coppolillo + 1.06.22 80. Djavanian + 1.07.20 81. Brignoli + 1.09.20 82. Perona + 1.12.05 83. Colombo + 1.12.06 84. Zanette + 1.13.37 85. Vatteroni + 1.14.38 86. Cipollini + 1.14.45 87. Casarotto + 1.17.37 88. Uria + 1.19.09 89. Frigo + 1.19.24 90. Ouchakov + 1.20.07 91. Baffi + 1.21.04 92. Velo + 1.23.23 93. Hodge + 1.23.38 94. Manzoni + 1.24.06 95. Baldinger + 1.24.41 96. Sierra Pena + 1.24.55 97. Casagrande Filippo + 1.25.01 98. Vidal + 1.25.56 99. Davidenko + 1.26.14 100. Rodrigues Quintino + 1.26.40 101. Salvato + 1.26.45 102. Boscardin + 1.27.33 103. Milesi + 1.29.57 104. Abdujaparov + 1.30.46 105. Gorini + 1.30.48 106. Pelliconi + 1.33.26 107. Artunghi + 1.37.38 108. Calcaterra + 1.38.23 109. Crepaldi + 1.39.45 110. Lombardi + 1.41.38 111. Conti + 1.42.03 112. Casagranda Stefano + 1.42.23 113. Andriotto + 1.43.37 114. Brognara + 1.43.59 115. Kjaergaard + 1.45.46 116. Magnusson + 1.52.00 117. Contrini + 1.53.38 118. Scirea + 1.55.52 119. Cauz + 1.56.31 120. Johnsen + 2.00.07 121. Moller + 2.10.42 122. Cerezo + 2.10.44 123. Forconi + 2.11.48.
INTERGIRO 1.Fabrizio Bontempi 38.46.38 2. Guidi + 0.07 3. Piccoli + 1.08 4. Bettin + 1.13 5. Bramati + 1.14 MOUNTAINS 1. Piccoli 37 pts 2. Tonkov 30 3. Ugrumov 16 4. Massi 14 5. Rebellin 12 TEAMS 1. Carrera 201.38.46 2. Gewiss Playbus + 0.21 3. Mapei-GB + 2.15 4. Festina Lotus + 6.43 5. Polti +12.37 POINTS 1. Guidi 168 2. Lombardi 100 3. Rebellin 88 4. Cipollini 79 5. Zaina 75 6. Spruch 74 7. Casagrande 70 8. Piccoli 67 9. Zanette 67 10. Missaglia 63