The objective of this research was to investigate the effects of a natural herb extract1 (HE) on the general growth performance and the incidence of muscle abnormalities (white striping and wooden) of broiler chicks. A total of 504 one-day old chicks (Ross 500) were used in the experiment and randomly partitioned into 3 treatments with 7 replicates in each (24 chicks per replicate). Three experimental diets (C: regular feed; T1 and T2 (supplemented with HE at levels of 0.20 and 0.30 ml/L, respectively). The herbal extract was supplemented in drinking water. Feed intake, body weight and feed conversion ratio were monitored at days 14, 28 and 42 of the feeding trial. Moreover, the yield of visceral organs, carcass cuts, and the incidence of muscle abnormalities were evaluated at different ages of slaughter (34, 41and 48 days). Results showed that weights, feed conversion ratios (FCR) and dressing percentages (DP) increased (p<0.05) in birds supplemented with herb extract compared to control birds. However, HE supplementation had no significant effects on carcass cuts and some visceral organs. Meat quality was improved by HE supplementation as the incidence of white stripping (WS) and WS plus wooden meat cases dramatically reduced, in particular at 34 days of age, day of slaughter. It can be concluded that feeding the herbal extract has significant positive effects on broilers general performance, feed efficiency and meat quality.