Brucellosis is one of the world''s most widespread zoonosis. We determined the sero-prevalence and risk factors for brucellosis in humans and their animals in Kajiado and Kiambu Counties of Kenya through simultaneous cross sectional surveys. The current study simultaneously investigated the linkage in sero-prevalence between humans and their animals within the same household at the same time. A human prevalence range of 2.2%-14.1% is reported while the prevalence in animals was 1.2%-3.4%. Having animal contact as well as handling hides and skins (OR =6.6, 95% CI: 4.5-9.7) predisposed humans to exposure to brucellosis.