Clinical efficacy of IPM/CS against urinary tract infections (UTI) was evaluated on 19 patients with malignancies (bladder tumor: 15, prostate cancer: 3, uterus cancer: 1) and 1 patient with a benign disorder (ureter stenosis) who had undergone ureterocutaneostomy between January, 1988 and December, 1990. Their ages ranged from 42 to 79 years. Postoperatively, they had UTI with pyuria of greater than or equal to 5/hpf and bacteriuria of greater than or equal to 10(4)/ml. IPM/CS was administered at a dose of 0.5 g (0.25g/0.25 g) twice a day through intravenous drip infusion. Its efficacy was evaluated according to the UTI criteria for clinical evaluation as ruled by the Japanese Society of Chemotherapy. Overall clinical value was rated "excellent" in 4 (20%), "moderate" in 9 (45%) and "poor" in 7 (35%) cases for a total of 65%. The efficacy by types of infection was 33% and 70.6% in the group of single infection and in the group of mixed infection, respectively. As to bacteriological efficacy 34 of the 38 strains (89.5%) isolated were eradicated following its administration. The eradication rate was 84.6% for P. aeruginosa, and 84.6% for E. faecalis. Microbes which appeared after its dosing amounted to 6 classes of 17 strains, 6 NFB strains of which were identified. As a side effect, elevation of serum GPT (5%) was noted. Regardless of the underlying conditions (malignant diseases and ureterocutaneostomy), clinical efficacy of IPM/CS was appreciable. In addition, the MIC for (P. aeruginosa, E. faecalis) of IPM/CS was lower than that of PIPC.