The safety of the UK anthrax vaccine in British service personnel was evaluated by a retrospective cohort study of randomly selected personnel from five Royal Air Force bases by investigating adverse medical events and consultation rates for a period before and after vaccination. Vaccination acceptance rate varied from 27 to 89% (P=0.0001). In the vaccinated cohort 11.1% (n=368) reported side-effects. The number of consultations in the year prior to vaccination (P=0.04) and RAF base (P=0.0085) were associated with side-effects. Only the RAF base remained a statistically significant factor (P=0.007) after adjusting for other factors. The anthrax vaccine resulted in mild side-effects in 11%, and no serious side-effects were observed. Acceptors of vaccine did not have significantly more medical consultations following vaccination than their unvaccinated counterparts.