The sensitivites of urinary pathogens from general practice and from hospital to a range of antimicrobial drugs have been recorded for the period 1971-8. There have been changes in the proportions of the different bacterial species and in their sensitivites to antibiotics. In particular, the position of ampicillin/amoxycillin and cephalosporins has deteriorated, partly because more resistant species have somewhat increased in prevalence and partly because the usually sensitive species, such as Escherichia coli, have become more resistant. Over the period 1971-8 the sensitivity of urinary pathogens, whether in general practice or in hospital, to co-trimoxazole and to trimethoprim has been maintained at a high level.