NEW YORK (REUTERS).- Microsoft Corp co-founder Paul Allen, who has been treated for non-Hodgkin's lymphoma, said on Thursday he is committing most of his estimated $13.5 billion fortune to philanthropy after his death.

Allen follows in the footsteps of former business partner Bill Gates and billionaire investor Warren Buffett, who have both pledged the vast majority of their wealth to philanthropy.

Allen, the 37th richest person in the world according to Forbes magazine, co-founded Microsoft in 1975 with Gates and resigned as an executive in 1983 as he overcame a first bout with cancer.

He has been involved with philanthropy in the U.S. Pacific Northwest for 20 years, largely through his Paul G. Allen Family Foundation, handing out more than $1 billion in grants and funding for local projects.

"Today I also want to announce that my philanthropic efforts will continue after my lifetime," said Allen in a statement. "I've planned for many years now that the majority of my estate will be left to philanthropy to continue the work of the Foundation and to fund nonprofit scientific research."

He gave no details of how his fortune would be directed to philanthropy after his death. Unlike the Gates Foundation, which has an independent $34 billion endowment for grant-making, Allen funds his own foundation's grants directly.

Born and raised in Seattle, Allen has close ties to the region. He owns the Seattle Seahawks American football team and is a minority owner of the Seattle Sounders soccer team. He created the Experience Music Project pop museum in the city and is leading the development of a run-down area near Seattle's Lake Union into a center for biotech research.

Since announcing his non-Hodgkin's lymphoma diagnosis last November, Allen has successfully completed a course of chemotherapy and currently has no medical issues, his spokesman said.

(Reporting by Bill Rigby, editing by Vicki Allen)