Berge said that proceeds from next month's second installment in the 'sale of the century' auction of the YSL-Pierre Berge collection, are to go entirely to HIV research and to the fight against AIDS.
Speaking ahead of the November 17-19 sale of the last items in one of the world's greatest private collections, YSL's onetime lover and business partner pledged 10 million euros (14.8 million dollars) over five years to France's largest private anti-AIDS group, Sidaction, which he heads.
"I want to again prove my commitment to the battle against AIDS," Berge told a media conference. "The fight against an epidemic as serious as AIDS must be shared between us all."
The donation is the largest to the French group in 15 years.
"It is a misconception to think AIDS is like other illnesses," Berge said. "We are not at the end of the tunnel, we are traveling further down the tunnel."
Some of the pledged funds will be raised at next month's YSL-Berge sale, expected to fetch between three to four million euros, which is far less than the record-smashing 700-item February sale that raised 342.5 million euros (491.9 million dollars), the biggest private art sale in history.
Works to be auctioned in November are largely from the pair's country hideaway on the Normandy coast, a three-storey place with a sea view built in 1874 for wealthy Americans that the two had redecorated to evoke writer Marcel Proust's "In Search of Lost Time".
Commenting on the larger February sale, Berge told AFP he did not yet know how much of the benefits would go to research on the HIV virus.
He also announced the creation of a special fund to oversee his donations as well as a specialist anti-AIDS committee that includes 2008 Nobel Medicine winner Francoise Barre-Sinoussi.
"Research has gone a long way since the 1980s, but so much remains to be done," she said. "Thanks to this donation we will be able to continue the battle."
The first February chapter in the once-in-a-lifetime YSL sale smashed 25 records for artists as well as setting new ceilings in Art Deco and silver.
A business tycoon, arts patron and committed left-winger, Berge opted to sell the collection amassed over a lifetime after Saint Laurent's death in June last year aged 71.
He pledged at the time to offer the proceeds to fight AIDS and to a foundation honoring Saint Laurent's work.
"I am a man of conviction," he said Tuesday. "I have always tried to be faithful to what I believe in, to act in accordance with my ideas.
"I know full well you have to have money to defend values, so in the light of these values, money in itself is of little importance."