The experimental materials comprised 400 Ross 308 chickens (200 ♂ and 200 ♀), divided randomly into four groups kept in 16 pens, as follows: a negative control group (I) – a diet without additives, a positive control group (II) – a diet supplemented with a combination of the antibiotic growth promoter flavomycin (10 mg kg⁻¹ feed) and the coccidiostat robenidine (500 mg kg⁻¹ starter and grower feed), and two experimental groups – diets supplemented with chemically standardized propolis – 10 mg kg⁻¹ feed in group 3 and 50 mg kg⁻¹ feed in group IV. The body weights of chickens were determined once a week. Feed intake, mortality and culling rates were monitored regularly. At the end of the experiment, on day 42, 12 chickens (6 ♂ and 6 ♀) were selected from each group for slaughter and carcass quality analysis. The final body weights of chickens, feed intake (kg) per kg body weight and carcass weight during the rearing period did not differ significantly between groups. The lowest feed intake per kg lean meat was noted in chickens fed a diet with 50 mg propolis/kg feed (3.457 kg), and the highest – in broilers fed a diet with 10 mg propolis/kg feed (3.611 kg). The weight of carcass and selected carcass parts (neck, breast, legs) tended to increase in chickens that received propolis, although the noted differences were statistically non-significant. The percentage content of legs in the carcass was significantly lower in chickens fed a diet with an antibiotic growth promoter (AGP). The legs of chickens fed 50 mg propolis had a significantly higher muscle content and a lower fat content, compared with the legs of birds fed a diet with AGP.