Organic farming of poultry has increased in recent years as the prophylactic use of antibiotics has come into disfavor. This study was conducted to explore the antiparasitic effect of a methanolic extract of Peganum harmala in broilers challenged with coccidiosis. For this purpose, 200 1-week-old broiler chicks were divided into five treatments: negative control (basal diet, Ph-0/NC), positive control (basal diet with coccidiosis challenge, Ph-0/C), and three groups challenged with coccidiosis and supplemented with P. harmala at the rate of 200 mg L(-1) (Ph-200), 250 mg L(-1) (Ph-250), and 300 mg L(-1) (Ph-300) drinking water. Each group had three replicates of ten chicks each. Challenge with standard dose of the larvae of coccidiosis and supplementation of P. harmala were initiated on day 14 until 35 days of age. As expected, the results revealed that weight gain, feed intake, and feed conversion ratio (FCR) were depressed significantly in Ph-0 group with significant mortality percentage. Weight gain, total body weight, and FCR increased linearly with increasing dose of P. harmala with the exception of feed intake. The growth and feed efficiency of Ph-0/NC was better in Ph-0/NC compared to that in Ph-0/C and comparable to that in P. harmala-treated birds. Similarly, mean ooccytes per gram (OPG) decreased linearly (P < 0.05) in supplemented groups compared to that in Ph-0/C. Histological evidences showed that cecal lesion and leucocyte infiltration decreased markedly in supplemented groups of P. harmala specifically the Ph-300 group compared to those in Ph-0/C. From the present experiment, we concluded the anticoccidial effect of P. harmala in broiler chicks.