The study was conducted to investigate the effects of different levels of buckwheat seed (BWS) with black cumin seed (BCS) supplementation on the performance, serum lipid profile and intestinal bacterial flora in broiler chicks. One hundred and twenty day-old Cobb-500 broiler chicks were randomly allotted equally to four experimental groups, designated T 1 (untreated control, no BWS and BCS); T 2 (10% BWS + 1.5% BCS); T 3 (20% BWS + 2.5% BCS); and T 4 (30% BWS + 3.5% BCS), respectively. The study lasted for 30 days. Average bodyweight, weight gain, total feed intake, feed conversion ratio (FCR), and serum lipid profile (serum total cholesterol, HDL-cholesterol, triglycerides) were determined and intestinal bacterial flora (total viable bacteria, Escherichia coli, Salmonella and Lactobacillus sp.) were counted. The results of the study showed that BWS and BCS significantly improved final bodyweight gain of group T 2 compared with the control group. Higher levels of buckwheat and black cumin did not improve growth performance of the chicks. Serum cholesterol and triglyceride concentrations significantly decreased with an elevation of HDLcholesterol concentration as the level of BWS and BCS increased. In BWS diets supplemented with BCS pathogenic bacteria, E. coli and Salmonella spp. were suppressed. These findings suggest that 10% BWS with 1.5% BCS supplementation to broiler ration could be considered an alternative to hazardous synthetic antibiotics for safe poultry production.