Summary:The haematological effects following ingestion of shellfish exposed to crude oil polluted water or the pollutant perse were investigated in albino Wistar rats. Feeding of four groups of rats for 28 days duration with two reference casein or shellfish protein control diets (Group A and B), and two test diets (Group C and D) supplemented at varying levels with shellfish which had been previously exposed to crude oil polluted water and the oral gavaging with crude oil at the rate of 3, 6 and 9 ml/kg body weight per day to three groups (groups II, III and IV respectively) of rats for 7 days duration resulted in changes in packed cell volume (PCV), red blood cell (RBC) and white blood cell (WBC) counts, and haemoglobin concentration (Hb) of rats. Group C and D respectively fed 10% and 20% polluted shellfish diets recorded significant (P < 0.05) decreases in PCV and RBC counts while Hb concentration and WBC counts increased. Groups II, III and IV gavaged with varying doses of crude oil recorded significant (P < 0.05 -0.01) dose dependent decrease in PCV and RBC counts when compared to controls (group 1). Hb and WBC counts also increased for these groups but the increase was only significant for WBC counts (P < 0.05) when compared with controls. The results suggest that the ingestion of shellfish exposed to crude oil polluted water or the polluted perse results in haematotoxicity.