THE EVENTS of the past six years have made clear the need for prophylactic measures against rubella. In 1966, Parkman and Meyer and their colleagues1,2 reported the development of a live rubella vaccine which had been attenuated by passage in African green monkey kidney cultures. Clinical trials in susceptible children showed that the vaccine strain was immunogenic and produced very few reactions. Although virus excretion occurred in a proportion of the vaccinees, no transmission of infection was detected in susceptible contacts. Recently, further attenuated vaccines have been developed in different cell substrates,3 and, on account of the potential risk of nasopharyngeal excretion to pregnant women, most of the trials have so far been carried out in children in enclosed communities. Until more is known about the length of immunity from rubella vaccines, no firm decision can be made on the proper age for immunization against rubella. We therefore