Currently, there is primary and obligatory requirement to identify and introduce new and effective plants for producing natural antibiotics with high biological potentials and low side effects. Medicinal plants and phytobiotics which are compounds of plant origin, can be replaced like probiotics and prebiotics with growth promoter antibiotics [1]. Medicinal plants and their effective compounds can develop the useful microbial populations (e.g. lactic acid bacteria) and inhibit pathogenic and non beneficial microbes' colonization in the gastrointestinal tract, increase the length of villi and improve the performance of broiler chickens [2]. Harmala with the scientific name of Peganum harmala is a perennial and non fluff plant from the family of Nitrariaceae. Alkaloids are the active compounds of harmala. They include Harman, Norharman, Harmine, Harmalol, Harmaline, Vasyzin and Vasyzinun [3]. It has been reported that harmala extract increased the relative weight of liver in broilers [4]. In this study, 160 laying Japanese quails at 50 weeks of age were used in a completely randomized design with 4 treatments and 4 replicates of 10 birds in each. The experimental treatments included control diet (with no feed additive), diet containing 0.02 percent Virginiamycin as growth promoter antibiotic, diet containing 0.25 percent Peganum harmala seed powder and diet containing 0.50 percent Peganum harmala seed powder. At the end of experimental period (60 weeks of age), two birds from each cage with the closest body weight to the cage mean weight were selected and slaughtered after recording their live body weights and their carcass component weights including breast, thigh, back, neck and abdominal fat and also internal organ weights including heart, liver and gizzard were measured in proportion to live body weight. The data were analyzed in a completely randomized design using GLM procedure of SAS. Comparison of means was conducted by Duncan's multiple range rest. The result
