Providencia stuartii has emerged as a significant nosocomial urinary tract pathogen. An increase in the number ofProvidencia isolates from urine cultures prompted an investigation into the possibility of an outbreak due to this organism. A high proportion of patients studied had urinary devices. Four wards were screened at two time periods to ascertain the prevalence ofProvidencia stuartii in urine cultures. Biotype, serotype, antibiogram and plasmid content were determined for eachProvidencia isolate. Of 129 patients initially sampled 22.5 % were found to harborProvidencia stuartii. Biotyping, serotyping and antibiograms indicated an epidemic strain was not present. Similar results were obtained when the wards were screened a second time, with 25.4% of urine cultures found to containProvidencia stuartii. By plasmid analysis the isolates could be grouped into one of ten profiles. A correlation could be made between urease activity and the presence of a large plasmid. No association however could be made between a particular plasmid profile and antibiogram. The data indicate that an epidemic strain ofProvidencia stuartii was not present. The source(s) of the endemicProvidencia stuartii strains remain unknown.