In a previous paper, we have noticed the effectiveness of two further attenuated measles vaccines, i.e. AIK-HDC and Edmonston- Zagreb- HDC. In the present study the same strains are comparatively used for immunization of a limited number of children under 9 months of age. A seroconversion of 100% was observed. Following reimmunization, a significant increase of circulating antibodies for both strains was recorded. Two combined measles-mumps-rubella (MMR) vaccines were also produced by using the same measles strains. The seroconversion following utilisation of MMR prophylactics in susceptible children was 98.8 and 97.3 for AIK and Edmonston- Zagreb strains respectively.