Sein Win (Burmese: စိန်ဝင်း, pronounced [sèiɰ̃ wɪ́ɰ̃]) is a Burmese politician, who served as Chairman of National Coalition Government of the Union of Burma, a "government in exile".

He was made unofficial Prime Minister of the Union of Burma, on being elected by the 1990 People's Assembly known as the National Coalition Government of the Union of Burma, a former government-in-exile.

His father Ba Win, was the elder brother of General Aung San and was part of the cabinet of Aung San.

Ba Win was assassinated in 1947, together with Aung San and most of the members of the cabinet, just before Burma gained independence.

Sein Win received his Bachelor of Science (Hons) degree in mathematics from University of Rangoon in 1966 .