Aim: Combined vaccines have an increasingly important role to play in delivering these antigens acceptably. We describe the immunogenicity and reactogenicity of a combined DTPa-HBV-IPV vaccine (diphtheria, tetanus, acellular pertussis, hepatitis B, inactivated poliovirus (DTPa-HBV-IPV: Infanrix penta) ) when administered for the primary vaccination of infants resulting from a study where the primary objective was to demonstrate non-inferiority of the immune response induced by DTPa-HBV-IPV using an industrial-scale IPV production process.Methods: Three hundred and fourteen infants received primary immunisation with DTPa-HBV-IPV at 2, 4 and 6 months of age. Routine Haemophilus influenzae immunisation was performed at 2 and 4 months of age at a separate injection site. Blood samples were taken at 2 and 7 months of age. Reactogenicity was assessed using diary cards for 7 days after each dose.Results: One month after the primary course, at least 98.9% of subjects achieved seroprotective antibody concentrations/titres against diphtheria, tetanus, hepatitis-B and polio types 1, 2 and 3. More than 97% had a vaccine response to pertussis antigens. The incidence of local injection site reactions after DTPa-HBV-IPV was similar to that for the Haemophilus influenzae vaccine site. General reactions of Grade 3 intensity were uncommon.Conclusions: The DTPa-HBV-IPV vaccine is a new combination of vaccines previously available separately, with established effectiveness and safety profiles. Combined vaccines reduce storage requirements and minimise the number of injections required, thereby reducing distress for infants and parents. DTPa-HBV-IPV was immunogenic with an acceptable safety profile and could replace separate administration of DTPa, HBV and IPV vaccines in infants.