The incidence of urinary tract infection in aged female hospital patients is very high in those with co-existing prolapse conditions. Of the 116 patients examined 30 had definite vaginal descensus or uterine prolapse and 22 of these patients had urinary tract infection. Even slight changes as laxity of vaginal wall and tendency to descensus increases the incidence of urinary tract infection. There is a smaller group of patients with urinary tract infection, characterized by therapy resistance and a continuous infection, in which no correlation to prolapse conditions could be found. It is believed that prolapse conditions are important in promoting benign urinary tract infection in aged female hospital patients but not significant in cases with a continuous, therapy resistant infection, apparently having a true pyelonephritis. Residual urine, bladder capacity and micturition pressure were measured and correlated with prolapse conditions and urinary tract infection.