The effect of dietary betaine supplementation during the finishing of broilers fed methionine adequate diet on the growth performance, carcass quality and meat chemical composition was assessed. A total of 300 one-day old Cobb 500 chickens were divided in three groups (n= 100) and included in the trial at the age of 4 weeks. Group I was chosen as control, while the diet of Group II and Group III was supplemented with betaine (Betafin ® S1) in amount 1 g/kg feed and 2 g/kg feed, respectively. The birds were fed the experimental diets until 6 weeks of age. Betaine supplementation showed no consistent effect on the growth performance in the broilers. During the first week of the trial, higher live weight (P<0.01), weight gain (P<0.001) and improved feed conversion (P<0.001) were observed in the birds receiving 2 g/kg betaine, while in the second week betaine did not have such positive effect on these parameters. Тhe carcass yield and the proportion of the edible parts were not affected, whereas the percentage of the heart increased in the betaine supplemented groups (P<0.05). Regarding meat composition, betaine showed beneficial effect associated with considerable increase of the protein in breast and thigh.