This report describes why the 1994 measles/rubella immunisation campaign was necessary, reviews its implementation, and provides information on its impact in Scotland where 60,504 children were immunised. Data on suspected adverse reactions to the measles/rubella vaccine are also presented. A large UK measles epidemic was predicted by independent researchers, and action in response was planned in accordance with the recommendations of the Joint Committee on Vaccination and Immunisation. As a result, the epidemic predicted for England and Wales was averted and the epidemic which had occurred in the West of Scotland was prevented from spreading to the East. Laboratory-confirmed cases of measles and rubella are now rare in all parts of the UK, especially in the age group targeted by the campaign. Most reported adverse reactions were mild and self-limiting: only one child per 6,700 vaccinated in the UK was reported to have suffered any adverse reaction. Immediate, serious reactions were either allergic or were described as convulsions (most associated with immediate syncope); all of these children recovered fully. Later onset neurological problems were reported at rates no higher than expected from normal population incidence.