AIM To measure measles-mumps-rubella (MMR) immunisation status of a birth cohort at 18 months of age. METHOD All children born in Christchurch in June, July and August 1995 who were alive at 18 months of age (n = 999), were matched with MMR immunisation benefit claims. Those not listed were traced. RESULT The final immunisation coverage rate was estimated at 85%. CONCLUSION An 85% coverage rate at 18 months fell well short of the Immunisation 2000 target of 95% coverage by two years of age.