The comparative efficacy of the three mumps vaccine strains (Jeryl–Lynn, Urabe and Rubini) was conducted in an Asian population from data arising from an epidemiological investigation of seven institutional outbreaks of mumps in Singapore. Demographic information (gender, age, ethnic group), clinical presentation and vaccination history (date and place of mumps vaccination, type of mumps vaccine received) of all children who attended the six childcare centres and one primary school where outbreaks of 20 or more cases of mumps occurred in 1999 were collected. The attack rate of the unvaccinated group and the attack rates of the vaccine groups (for each vaccine strain) were determined and the vaccine efficacy of the three vaccines calculated. The vaccine efficacy of the Jeryl–Lynn strain, Urabe strain and Rubini strain mumps vaccine were 80.7, 54.4 and −55.3%, respectively. Rubini strain mumps vaccine conferred no protection and has since been deregistered in Singapore.