In order to investigate the therapeutic effects of Lishengsu, a domestic preparation of recombinant human granulocyte colony stimulating factor, the recovery of leukopenia was observed in 58 patients with malignant tumors after chemotherapy. In these patients, 7 cases were in first cycle of chemotherapy and 51 were given in repeated cycles. When blood leukocyte level decreased to less than 3x10(9)/L, Lishengsu was subcutaneously injected for 3-5 days at a dose of 75 microgram or 150 microgram per day. The results showed that Lishengsu remarkably alleviated the degree of leukopenis and accelerated the leukocyte counts recovered to normal level. The promotive effects of Lishengsu to recovery of leukopenia were dependent on degree of leukopenia at start of administration of Lishengsu. The curative effect of Lishengsu to chemotherapy-induced leukopenia was reliable with slight side-effects