The clinical usefulness of KRN 8601 (rhG-CSF) was evaluated in patients with neutropenia induced by chemotherapy for non-Hodgkin lymphoma in a double-blind study. The same chemotherapeutic regimens repeated for twice in 3 to 4 weeks interval. During the first cycle of chemotherapy, changes of leukopenia (neutropenia) were observed, and KRN 8601 at a dose of 75 micrograms/body or placebo was started to administer subcutaneously 72 hours after the termination of the second cycle and continued for 14 days. Elevations of nadirs of absolute neutrophil counts (ANC) and significant shorting of neutropenic periods of ANC below 2,000/mm3 were observed with patients given KRN 8601. KRN 8601 is significantly superior over placebo (p less than 0.0001), while overall safety evaluation showed no significant difference between the two groups. All the above results indicate that KRN 8601 is extremely usefull for the neutropenia induced by chemotherapy.