SummaryRubella vaccine, prepared with the attenuated strain Cendehill 51, was injected to 33 children and 5 adults belonging to a closed community. Seroconversions were obtained in all children (21) who did not possess any antibody before vaccination, as detected by the inhibition of hemagglutination test. Among the 17 individuals who possessed a residual level of antibodies, due to previous natural immunization, 7 showed a rise in antibody titre following vaccination.