Objective: To evaluate, in an open study, the immunogenicity, safety and reactogenicity of a birth dose of hepatitis B vaccine followed by a three-dose course of diphtheria–tetanus whole-cell pertussis–hepatitis B vaccine, extemporaneously mixed with Haemophilus influenzae b (Hib) vaccine. Methods: At 2, 4 and 6 months of age, a single group of 120 Colombian infants were enrolled in this study to receive a regimen consisting of three doses of the combination vaccine following a dose of hepatitis B vaccine at birth. Results: Seroprotection/vaccine response rates to all vaccine antigens was 98–100% 1 month after completion of the full vaccination course. The vaccine had an acceptable reactogenicity profile and the incidence of reported local and general symptoms decreased with the administration of subsequent vaccine doses. Conclusion: The mixed DTPw–HB/Hib vaccine was safe and well-tolerated, with high immunogenicity against all component antigens. Compared with previous studies, reactogenicity did not increase with the additional dose of hepatitis B vaccine given at birth. The DTPw–HB/Hib combination can be used to provide primary vaccination of infants who have already received a first dose of hepatitis B vaccine at birth.