In 1992 it was decided to implement vaccination against Haemophilus influenzae type b (Hib) in the Norwegian vaccination programme. The chosen vaccine consists of Hib-polysaccharide conjugated to tetanus toxoid. To suit the Norwegian vaccination schedule, Hib-vaccine was given together with vaccine against diphtheria, tetanus and pertussis (DTP) at three, five and ten months of age. Since all earlier studies with the Hib-vaccine have used other time schedules, a pilot study was conducted to test antibody response and side effects when using the Norwegian schedule. 44 infants were vaccinated with Hib-vaccine and DTP at three, five and ten months of age. Blood samples showed that 95% had protective antibody titer against Hib after two doses, 100% after three. The response to the other antigens was adequate. There were only minor side effects. After introduction of the Hib-vaccine the incidence of invasive Hib-infection in children below three years of age has decreased considerably.