This study was conducted to compare the efficacy of herbal methionine (HM) to synthetic methionine (SM) in broiler chickens. The herbal methionine (Meth-o-Tasr®) was supplied by lntas Pharmaceutical Limited, India. The HM and SM were added to standard diets at 0, 0.5, 1.0 and 1.5 kg/ton of finished feed and fed to 168 Arbor Acre broiler chickens. After seven days pre-experimental period, the birds were randomly allocated to seven isonitrogenous and isocaloric dietary treatments in a completely randomized experimental design with factorial arrangement of treatments. Each treatment was replicated four times with six birds per replicate. The trial lasted for 56 days and was divided into two phases; the starter phase and the finisher phase. The final body weight, body weight gain, feed intake and feed conversion ratio (FCR) of the birds were determined on a weekly basis. At the end of the feeding trial, two birds per replicate were randomly selected and slaughtered for the determination of carcass quality traits and biochemical and haematological profiles. The average final body weight, body weight gain and average feed intake of the birds fed on diets supplemented with SM were significantly different (P ≤ 0.05) from those fed on diets supplemented with HM at both starter and finisher phases. The birds on SM supplemented diets gained more body weight and consumed more feed than those on HM supplemented diets. Feed conversion efficiency was not affected (P ≥ 0.05) by the dietary methionine source. Birds on SM supplemented diets had better (P ≤ 0.05) carcass yield than those on HM and control diets. Dietary HM supplementation did no significant (P ≥ 0.05) effect on any of the biochemical or haematological variables determined. It can be concluded from this study that, though no detrimental health effects, were detected, dietary HM is not an effective substitute for synthetic methionine for optimum production performance.