Review of all 126 children admitted to the communicable diseases unit with whooping cough during the epidemic in 1978 showed that two had received two doses of triple vaccine and only one had had full primary immunisation against the disease. None of these three children suffered complications of the disease. Of the 123 children who had not been immunised against pertussis, however, 66 had had one or more complications. In Birmingham the dramatic decline in immunisation against pertussis has been accompanied by a fall in acceptance rates for diphtheria and tetanus immunization. Nevertheless, of the 62 children aged over 1 year in this series, 41 had been so immunised. These findings suggest that the apparently positive decision by parents to omit pertussis immunisation was misplaced, since immunisation does protect against the more serious complications of the disease. Furthermore, there is no firm evidence that pertussis immunisation of children without specific contraindications is associated with serious adverse reactions.