Than Nyein was born in Khanaung east village, Kyauktan Township in British Burma on 5 August 1937.

He worked for the Ministry of Health as a leader in the leprosy prevention group and as a township medical officer.

His medical licence was revoked and sentenced to 7 years in prison for participating in youth organization activities in October 1997.

[5] He disagreed with party secretary general Aung San Suu Kyi and advocated for major political decision that not to boycott 2010 elections.

[7] He was the brother-in-law of Khin Nyunt, then chief of military intelligence and Prime Minister of Myanmar from 2003 to 2004.