The effects of granulocyte colony-stimulating factor (G-CSF) and engraftment quality on the rate of hematopoietic system recovery were assessed in patients with solid tumors and lymphoproliferative diseases after autologous hematopoietic stem cell ransplantation. Treatment with autologous hematopoietic stem cell transplantation was performed in 40 patients for non- Hodgkin's lymphoma (n= 20), Hodgkin's lymphoma (n= 8), multiple myeloma (n= 8), and breast cancer (n=4). In 20 patients with solid tumors and ymphoproliferative diseases, treatment with autologous hematopoietic stem cell transplantation was followed by G-CSF therapy (experimental group). Another 20 patients with solid tumors and lymphoproliferative diseases were treated with autologous hematopoietic stem cell transplantation without G-CSF therapy (control group). The two patient groups were matched for age, sex, diagnosis, number of chemotherapy courses, and engraftment quality (nucleated cells or CD34+ cells). The experimental group received G-CSF in a dose of 5 μg/kg body weight subcutoneous from day 1 of autologous hematopoietic stem cell transplantation until leukocyte count increase to > 1.0 x 109/L over three consecutive days. Nonparametric tests (x2-test, median test, extended median test) were used in statistical analysis. The hematopoietic system showed rapid recovery. Leukocyte count > 1.0 x 109/L was recorded on median day 11 (range 8-21) in the experimental group vs median day 12 (range 9-16) in the control group; gra-nulocyte count > 0.5 x 109/L on median day 12 (range 8-23) vs day 14 (range 10-16) in the control group; and platelet count > 20 x 109/L on median day 13 (range 8-80) vs day 11 (range 7-15) in the control group. Differences between the two patient groups were not statistically significant. G-CSF therapy administered after autologous hematopoietic stem cell transplantation did not result in faster leukocyte, granulocyte or platelet recovery. The patients receiving a relatively lower number of cells showed the same rate of recovery as those who received a higher cell number. The number of CD34+ cells per kg body weight did not correlate with the rate of leukocyte, granulocyte or platelet recovery.