From Feb. to Dec. 1985, 15 patients were treated with fetal liver cell transfusion (FLT). They were 10 cases with malignant tumors treated by chemotherapy (tumor group) and 5 with blood diseases (blood group). Under strict aseptic technique, 3 1/2-6 month old fetus was selected for preparing suspension of the fetal liver cells on the superclean table. The speed of FLT should be increased gradually from slow to rapid. There are 1.8 X 10(8)-4 X 10(12) fetal liver cells in a fetus of more than 5 months old, in which most are CFU-C. In the tumor group, after FLT, white blood cell, platelet and hemoglobin increased by 700-3,900/mm3, 5,000-116,000/mm3 and 0.5-2.0 gm/mm3 respectively. But in the blood group, they increased by 800-1,300/mm3, 14,000-84,000/mm3 and 0.4-11.0 gm/mm3. In most of the cases, these hematological indexes reached up to the highest in 2 weeks after FLT. It suggests that FLT can improve the peripheral blood picture obviously and stimulate bone marrow. Experiment confirms that there are considerable hematopoietic stem cells in the fetal liver, by which the functions of hematopoiesis and immunity are able to recover. It is more marked in the tumor group than in the blood group. FLT provides a favourable condition for high dose chemotherapy.