This study aimed to evaluate the probable effect of oil extract of black cumin seeds Nigella sativa L. on weight body and other body organs (pancrease, spleen, liver and kidney) and some blood parameters (Hb, PCV, WBCs, GPT and GOT).The extract was administrated orally for 30 days at (0.1, 0.2, 0.3, 0.4 ml/100 gm of body weight (b. wt.). day-1) to
adult male rats in addition to control group. Body and other organs weight for control and treated rats were measured. Results of experiment indicate that the extract decreased significantly (p> 0.05 ) the body weight in all groups in contrast with control group, while the weight of pancreas was increased significantly, spleen decreased significantly in 0.2, 0.3, 0.4 mg/gm of b.w. and liver was decreased significantly in 0.2, 0.3, 0.4 mg/gm of b.w, while the kidney was not affected in all treatments. Hematological picture, The result obtained revealed that there were a significant changes (p˂0.05) including Hb, PCV% and WBCs. Histological Examination of H&E sections of livers of all treatment showed vascular congestion of liver in 0.1 and 0.2 ml/gm b.w, Spleen tissue of normal rat administered N. sativa seed extract,
spleen showed hyperplasia in red pulps in all doses of plant extract. while the histological examination of kidney and pancreas showed normal intact histological structure in both control and treated group.