An Ahmadzay Ghilzay Pashtun from Paktia, Najibullah graduated from the College of Medicine in 1975. It took him ten years to complete his studies because of political activity and imprisonment as a party activist.

He was known on the campus for his skill in oratory, in particular for reciting poetry that enchanted the audience. For his athletic activity he was known as Najib the Bull (Najib-e-Gao). He was under the spell of Khybar at the same time that he was loyal to Karmal. In 1977 he joined the central committee and in 1978 the Revolutionary Council. After the Khalqis pressured the Parchamis, the former banished him to Iran as ambassador. Soon it dismissed him and deprived him of Afghan citizenship. Najibullah took away “about $300,000 of the embassy cash in addition to other valuables” (Sharq, Memoirs, 165). After the invasion he was made the head of KHAD; in 1981 he was promoted to membership in the politburo. At the same time that KhAD brutalized inmates, Najibullah, its director, embraced youngsters in kindergartens or gave sermons to elders summoned to his presence.