In total six hundred, day-old Ross 308 male broiler chickens were fed one of four diets containing 0, 10, 30 or 50 g of Corynebacterium ammoniagenes- derived single cell protein (SCP) per kg for 35 days to investigate the effect of graded level of SCP on growth performance, organ weights, serum and tibia characteristics, and meat quality. In each treatment were 5 replicates, 30 chickens per replicate. Graded levels of dietary SCP did not affect (P > 0.05; linear or quadratic) daily weight gain of broilers at all ages. However, chickens fed a diet containing 10 g SCP · kg⁻¹ had higher (P < 0.05) body weight gain in comparison with the control group at days 1–21. Dietary SCP linearly lowered (P < 0.05) feed intake at all ages, but quadratically enhanced feed conversion ratio at days 1–21 as the SCP levels in diets increased. Chickens fed the diet containing 10 g SCP · kg⁻¹ consumed more (P < 0.05) at days 22–35 and 1–35 as compared with the control group. Dietary SCP did not affect (P > 0.05) the relative weights of various organs, serum and tibia characteristics, and meat quality parameters. In conclusion, the obtained results suggest that C. ammoniagenes-derived SCP can be added at the level of 1% to broiler diet as a non-conventional protein source without any negative effects on blood and bone characteristics, and meat quality.