ABSTRACT Hepatitis B, an important public health problem, globally affects 240 million people. Annually, an estimated 650,000 people die from its liver complications. It is endemic in much of the developing world, where 8 – 10% of the population are infected. It has caused epidemics in parts of Asia and Africa. In Africa, 75 million people are affected by the virus, ranging from 13.6% in Nigeria to 5.7% in Ethiopia. The public health burden of HBV infection in Uganda is unknown, despite its long standing reputation as to be among the highly endemic countries of sub-Saharan Africa. Medical students are a group at high risk of getting and spreading HBV because their activities involve contact with patients, blood and other body fluids. No such study had been conducted at KIU-WC thus the study set out to assess the uptake, financial constraints and Hepatitis B knowledge as determinants of hepatitis B vaccine uptake among medical students in the institution. A total of 86 senior medical students took part where it was found that the uptake was at 25.85%, knowledge did not play a positive role towards uptake and financial constraints were found to be the major hindrance to vaccine uptake. It was concluded that, vaccine uptake was low and required intervention, knowledge did not improve vaccine uptake while financial implications hindered uptake.