© 2010 Islamic Azad Univerty, Rasht Branch, Rasht, Iran.This research was conducted to find out the effect of peppermint and basil as natural feed additives on broiler performance. The objective of the present study was to investigate the impact of the peppermint (Mentha pipreitae) and basil (Ocimum basilicum) as a feed additive on live body weight (LBW), body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR), carcass weight, abdominal fat and liver weight characterization of broiler chickens. A total of 210 broiler chicks (Ross 308 strain) were selected and divided into 7 treatments and 3 replicates based on completely randomized design. One day-old chicks were reared for 35 days. Feed and water were provided ad libitum. Chicks were divided into seven treatments (30 birds each). Each treatment contained three replicates of 10 birds. Each group of birds were supplied with 0% (T1-control) 0.5% (T2), 1.0% (T3) and 1.5% (T4) of peppermint and 0.5% (T5), 1.0% (T6) and 1.5% (T7) of basil as feed additive and control group was supplied with neither peppermint nor basil in their ratio. As a result of this study, mean LBW, BWG, FI, FCR and liver weight against T4 (1.5% peppermint) was significantly (P < 0.05) higher for broilers in the other group. But had there were non significant effect on the carcass, carcass yield and abdominal fat. Findings of the present study suggested that feeding peppermint and basil tend improve the growth performance and FCR of the broilers.