We examined the value of the CSF-HU preparation (colony-stimulating factor derived from human urine: P-100) to prevent or treat granulocytopenia induced by anticancer chemotherapy. Subjects were urogenital cancer patients who underwent two courses of the same chemotherapy regimen. Among these patients, we selected the subjects whose leucocyte counts were decreased to less than 2000/mm3 after the first course of anticancer chemotherapy. P-100 was administered from the following day of the end of the second course of chemotherapy at a dose of 8,000,000 units/day by intravenous drip infusion for 7 successive days. According to the global evaluation by consideration of changes in leucocyte and granulocyte counts, the utility rate by physicians was 52.4% (22/42), and that by a committee was 50.0% (18/36). No difference was seen in utility rate and efficacy rate according to P.S., cancer types and antineoplastic drugs used. Side effects were noted only in 2.3% (1/44) which was mild and transient fever. These findings suggest that P-100 is a very useful drug for prevention and/or treatment of granulocytopenia following cancer chemotherapy.