Background & Aim: Medicinal plants is very potential to be used as a supplementary feed as well as feed additive in broilers.This experiment was conducted to investigate the effects of milk thistle (MT) and thyme seeds (TS) on the performance in broilers. Experimental: In this study, 160 one-day-old (Ross 308) male broiler chicks were divided randomly into four major groups with 4 replicates based on a completely randomized design. Dietary treatments was included; i.e., (A) Control, (B) diet with 20 mg per kg of MT, (C) diet with 20 mg per kg of TS and (D) diet with 20 + 20 mg per kg of MT and TS, respectively. The birds were reared for 35 days in wooden pens. Also, feed and water were provided ad libitum. Feed intake (FI) and body weight gain (BWG) were measured in 3 stage (one-14, 14-28 and 28-35 days) for each replicate and feed conversion ratio (FCR) was calculated. Results: At One to 28 days of age, feed intake, body weight gain and feed conversion ratio were no affected by dietary supplementation, while the percentage of abdominal fat was reduced by 3.14%, 3.11% and 3.32% for groups (B), (C), and (D), compared to group (A) 4.23%, respectively (P < 0.05). Birds fed the (D) supplemented treatment (MT plus TS) had the greatest FI and BWG levels (P < 0.05) than the control birds (group A) at 28 to 35 days. However, dietary supplementation (MT and/or TS) reduced (P < 0.05) the conversion ratio levels in the 28 to 35 days of study, and this effect was more pronounced for the (D) treatment (MT plus TS). Recommended applications/industries: In conclusion, the present research indicated that supplements of powdered thistle seeds and/or thyme seeds have a protective influence on the growth performance in broiler chicks. Manuscript profile