The 1994 national census reported a total population for this district of 111,537 in 16,989 households, of whom 55,693 were men and 55,844 were women; 19,587 or 17.56% of its population were urban dwellers. The two largest ethnic groups reported in Sayo were the Oromo (95.29%), and the Amhara (3.1%); all other ethnic groups made up 1.61% of the population. Oromiffa was spoken as a first language by 96.58%, and 2.79% Amharic; the remaining 0.63% spoke all other primary languages reported. The majority of the inhabitants observed Ethiopian Orthodox Christianity, with 50.7% reporting that as their religion, while 28.65% were Protestant, 10.32% Muslim, and 9.25% Catholic.