This experiment was examined the effect of splenectomy on the hematology in pregnant wistar rat. Only animals that had been shown regular 4-day estrous cycles for more than two cycles were used. The day after mating with the same male animal ws designated Day 0 of pregnancy. Spleen was removed from Day 0(early), 6(middle) and 13(late) of pregnant rat, respectively. Blood sample was collected at Day 1, 7, 14 and 21 of the pregnancy. 1. RBC was increased significantly(P<0.05) to the progress of pregnancy in control rat. The late splenectomized rats were decreased significantly(P<0.05) at Day 21 of pregnancy than control rats. 2. Hb was increased significantly (P<0.05) at 21th day of pregnancy in late splenectomized groups than others group. 3. In the late splenectomized rats, Ht was decreased significant (P<0.05) due to the progress of pregnancy and decreased significantly (P<0.05) at Day 21 of pregnancy in all splenectomized groups. 4. WBC was increased significantly (P<0.05) at Day 1 of pregnancy in splenectomized groups compared with control. 5. In differential leukocyte rate, the Basophils and Monocytes was not significantly changed. Neutrophils was increased significantly(P<0.05) at Day 14 and 21 than Day 1 and 7 of pregnancy in control. Lymphocytes was decreased significantly(P<0.05) in control due to progress of pregnancy. Neutrophils was increased and Lymphocytes was decreased significantly(P<0.05) in splenectomized groups compared with control.