SummaryA bacteriophage typing method of identifying strains of E. coli found in urinary tract infections has been developed. Eight phages were isolated from sewage and used to classify E. coli into 14 phage types. Certain types were found to cause a majority of the infections. Twenty of 40 phage typable cultures were typable serologically and no definite correlation was obtained. However, there were several phage types in each serological group. Several advantages in using phage to identify strains from urinary tract infections were pointed out.