A trial of protective efficacy which compared medium–titre Edmonston-Zagreb (EZ) measles vaccine (104.6 p.f.u.) from the age of 4 months with the standard Schwarz (SW) measles vaccine given from the age of 9 months was started in an urban community in Guinea-Bissau in 1985. Because trials of high–titre measles vaccine have found increased mortality among female recipients, we examined whether EZ medium–titre vaccine was associated with any long-term impact on mortality, suppression of T–cells, or growth. The mortality rate ratio over 5 years of follow–up was 1.12 for EZ children compared with children in the standard group (P = 0.63). Seventy–five percent of the children still residing in the area at 5 years of age took part in an immunological and anthropometric examination. There was no difference in T–cell subsets between the two groups. There was no difference in mid–upper–arm circumference, but EZ children were significantly shorter than the children in the standard group. In conclusion, medium–titre EZ was not associated with reduced survival or persistent immunosuppression.