The effect of saponin purified from Solanium anguivi Lam. fruits on haematology parameters of rats (Rattus novergicus) was investigated. Thirty six (36) rats (Rattus novergicus) of average weight (125± 12g) were divided into six (6) groups of six animals each designated as A (n=6, 2.0 ml distilled water), B (n=6, 20mg/kg saponin), C (n=6, 40mg/kg), D (n=6, 60mg/kg), E (n=6, 80mg/kg) and F (n=6, 100mg/kg). Saponin was administered orally once daily to groups B, C, D, E and F for (21) days while group A served as control. The animals were then sacrificed and blood was obtained for estimation of the data herein presented. Solanum anguivi fruit saponin had a significant reduction (P<0.05) in red blood cells (RBC), white blood cells (WBC) and Haemoglobin (Hb) concentration and the decrease was dose dependent. There was no significant difference in packed cell volume (PCV), basophil, lymphocyte and eosinophil. There was significant increase in neutrophil at 100mg/kg (P<0.05). The observed significant reduction in RBC and Hb concentration were indication of defective haematopoiesis and anaemia respectively. Therefore, saponins from S. anguivi fruits inhibit erythropoiesis.