To examine the effect of Lishengsu (rhG-CSF) on the recovery of leukopenia and control of infections after chemotherapy, twenty tumor patients were observed. When blood WBC decreased to less than 2.5 x 10(9)/L and ANC less than 1.5 x 10(9)/L after chemotherapy, Lishengsu was administered in a dosage of 150 micro g/day for 5 days or until WBC and ANC recovered to normal level. The changes of hemogram, body temprature, the signs of oral mucous membrane and lung were examined. The recovery of WBC and ANC in the Lishengsu group was much faster than that in the control group. The difference between the two groups was statistically significant (P < 0.01). The duration of fever was shorter and the healing of oral ulcers was faster in Lishengsu group than that in the control group (P < 0.05). The results indicated that Lishengsu in a low dosage and a short administration period could enhance the recovery of WBC and ANC efficiently, shorten the duration of fever, quicken the recovery process of oral ulcers and reduce the needs for supporting treatment in tumor patients after chemotherapy.