Feeding of powdered black seeds of historically famous medicinal herb, Nigella sativa L. has been shown to lower serum triglycerides and decrease egg cholesterol in laying hens. This study aimed to investigate effects of varying doses of N. sativa seed powder (0, 1.5, 2.5 and 3.0%) and acetone extracts (0, 1.5 and 3.0%) on feed intake, health, fat content, serum lipid profiles and population of intestinal microflora of broiler. Results revealed that N. sativa supplemented feed had no significant effects on feed intake, body weight, fat content and mortality rate. However, supplementation of 3.0% seed powder and 0.4% extract of N. sativa significantly (p<0.05) decreased serum cholesterol and triglycerides while elevating the HDL contents of broiler. N. sativa supplemented feed also suppressed harmful intestinal bacterial (Escherichia coli) population in the feces like. These results suggest that N. sativa seed might have potential as an alternative to synthetic feed additives to formulate low cost and environment-friendly diet for the broiler.