The present experiment was carried out to compare the effects of different levels of wild ginseng root powder on performance, immune responses and histological changes in internal organs of broiler chickens. A total of 288 broiler chicks (Ross 308) were used in a completely randomized design with 6 treatments including 4 replicates and 12 chicks per pen. Experimental treatments were included control treatment (without additive), Antibiotic treatment (100 mg/kg virginiamycin), 0.5 and 1% wild ginseng root powder, vitamin E (100 mg/kg), and vitamin C (500 mg/kg). Chicks received starter (1-10 days), grower (11-24 days) and finisher (25-42 days) diets. The studied parameters include body weight gain, feed intake, feed conversion ratio, carcass yield, relative weights of internal organs (breast, thigh, neck, abdominal fat, liver, heart, pancreas, gizzard), relative weights of the lymphatic organs (spleen and bursa of Fabricius), leukocyte count, intestinal microbial populations, intestine morphology, and antibody responses against Newcastle virus and sheep red blood cells (SRBC). Data were analyzed using ANOVA procedure of SAS. The results of experiment showed that body weight gain was not significantly different between treatments. There was not significant difference within treatments for feed intake, But there was a significant difference (P 0.05) among control group and ginseng groups for body weight gain during growing and final periods. Feed conversation ratio was not significantly different between treatments. there was a significant difference (P 0.05) between virginiamycin and ginseng groups. There was not significant difference among experimental groups for the relative weights of internal organs. There was a significant difference (P 0.05) for carcass percentage between virginiamycin and ginseng groups. relative weights of the lymphatic orga was not significantly different between treatments. There was no significant difference in antibody titer against Newcastle and SRBC. There was significant difference in the percentage of lymphocytes, heterophils, and heterophil to lymphocyte ratio in peripheral blood. The villus height of duodenum was significantly different between experimental groups. Keywords : Broiler chichens, Ginseng, Intestinal morphology, Immune response, Performance
