• The feasibility of giving measles vaccine mixed with either diphtheria-pertussis-tetanus (DPT) or DPT-poliomyelitis (DPTP) vaccine was investigated to simplify the routine Immunization schedule. Children 12 to 18 months of age, due for measles immunization, were given measles vaccine alone or mixed with DPT or DPTP. Their prevaccinatlon and four-weeks postvaccination serum samples were tested for the measles virus hemagglutination-inhibition antibody titer. Although 191 children completed the study, only 160 were initially seronegative. The seroconversion rates and geometric mean antibody titers in children given measles vaccine alone, mixed with DPT, or mixed with DPTP were 98%, 96.3%, and 96.4% and 41, 53, and 53, respectively. Local and systemic reactions were no more frequent in children given the mixture of vaccines than in children given DPTP alone. In summary, injecting measles vaccine mixed with DPT or DPTP did not diminish its immunogenic potency or increase adverse reactions. We believe that freshly mixed measles and DPT or DPTP vaccines can be given together, thus avoiding two separate injections.