The combination of hepatitis A virus (HAV) and hepatitis B virus (HBV) vaccinations can offer convenience, increased compliance and cost saving. We have studied the immunogenicity, reactogenicity and safety of combined hepatitis A and B vaccination in young adults (16-35 years old). Eighty healthy young adults were divided into two random groups. One group received the combined hepatitis A and B vaccine (HAB) in one arm while the other group was administered concomitant hepatitis A and B vaccines (HAV + HBV) in the right and left arms, respectively. The immunogenicity, reactogenicity and safety were assessed after each dose in both the groups. In local symptoms, the percentage of the combined HAB group was lower than the HAV + HBV group, and the general symptoms were noted in approximately 30% of each group without any significant difference. No serious adverse effects were noted. All the subjects were seropositive for antibody to hepatitis A virus (anti-HAV) after one dose of vaccine, and remained seropositive after three doses in both groups. The seropositive rate for antibody to hepatitis B surface antigen (anti-HBs) was significantly higher (84%) in the combined HAB group than the concomitant HAV + HBV group (62%), (p<0.05) after dose two, and all the subjects were seropositive (100%) after the third dose. The GMTs of anti-HAV and anti-HBs were not significantly different between groups 1 and 2 (p>0.1) except in month 6 when the GMT of anti-HBs was higher in HAB group (p=0.0039). The combined HAB vaccine was found to be safe, well tolerated and had less local symptoms in young adults. The immunogenicity and reactogenicity were similar to the concomitant HAV + HBV vaccines.