1. Rhazya stricta leaves and Nigella sativa seeds were fed to 7-d-old Hibro broiler chicks at 20 and 100 g/kg of the diet for 7 weeks. Although 20 and 100 g/kg N. sativa seed diets did not adversely affect growth, a decrease in body weight and feed efficiency and hepatonephropathy were observed in the chicks fed on the 100 g/kg R. stricta diet. 2. These changes, associated with macrocytic hypochromic anaemia, were correlated with alterations in serum aspartate transaminase' (AST) and alanine transaminase (ALT) activities and concentrations of total protein, albumin, globulin, cholesterol, calcium and other serum constituents. 3. The effect of 20 g/kg R. stricta diet on chicks was not associated with development of biliary hyperplasia or catarrhal enteritis after 7 weeks of treatment.