Hematopoietic recovery kinetics were evaluated in 34 children with therapy-refractory malignant tumors who underwent a total of 35 peripheral blood stem cell autografts (PBSCT) after marrow-ablative chemotherapy without total body irradiation. A negative correlation was found between the numbers of colony-forming units of granulocyte-macrophage (CFU-GM) infused per kilogram of the patients' body weight and the time of achieving an absolute granulocyte count (AGC) of 0.5 x 10(9)/l or a platelet count of 50 x 10(9)/l (granulocyte: r = -0.631, p less than 0.001, platelet: r = -0.590, p less than 0.001). The patients were classified into three groups; 14 patients who received less than 1 x 10(5) CFU-GM/kg (group A), 7 patients who received 1-3 x 10(5) CFU-GM/kg (group B), and 14 patients who received greater than or equal to 3 x 10(5) CFU-GM/kg (group C). The AGC recovered to 0.5 x 10(9)/l by 21 day in group A, 14 day in group B, and 10 day in group C. The platelet count recovered to 50 x 10(9)/l 102 in group A, 23 in group B, and 16 day in group C patients. The final platelet infusion was on day 60 in group A, day 12 in group B, and day 12 in group C. Transient decrease in the blood cell count developed in all patients 3 to 7 weeks after transplantation, and two cases developed reversible ITP. In the remaining patients, the recovered hematopoietic function was sustained for 1-48 months after transplant action.(ABSTRACT TRUNCATED AT 250 WORDS)