A multicentre prospective study of 933 patients being treated with ampicillin showed a rash incidence of 7·3%. The rash was commonest in women and patients suffering from viral infections. Most rashes were maculopapular and were not associated with features of true penicillin allergy. We conclude that the development of a maculopapular rash during or after treatment with ampicillin is not in itself a contraindication to future treatment with the penicillins.
↵* The collaborative study group was established at the instigation of Beecham Research Laboratories in 1968, in order to investigate the characteristics of the ampicillin rash in a prospective survey.