Due to problems such as soil pathogens, lake of suitable soils, shortage of fresh water for irrigation and better control on environmental factors, using hydroponic methods for vegetable production is increasing in the world. Generally, hydroponic systems can be divided into two groups according to its media: liquid media and aggregate substrate. The second type is more common. Besides their characteristics such as good draining, high water holding capacity, high ionic exchange and their devoid of weeds, pests and pathogens, media should be also cheap, accessible and preferably organic to be better recycled in nature. The objective of this investigation was to study possibility of using rice hull, saw dust, perlite and their combination with zeolite in soilless system as growing media and their effects on growth, yield, fruit quality, and nutrient concentration of bell pepper ( Capsicum annuum L.). A greenhouse experiment was conducted using a randomized complete block design with 9 treatments, 4 replication and two plants in each replication. Treatments (growing media) were consisted of: rice hull (100%), perlite (100%), coarse saw dust (100%), rice hull (75%) + zeolite (25%), perlite (75%) + zeolite (25%), saw dust (75%) + zeolite (25%), rice hull (50%) + perlite (50%), saw dust (50%) + perlite (50%) and rice hull (50%) + saw dust (5o%). Seeds were sown in a mixture of peat and perlite (4:1 v/v). Seedlings were tralanted at 3 true leaves into 5-liter volume pots filled with different substrates. Water and nutrient requirements of the plants were supplied using Johnson nutrient solution (50%), applied with a drip irrigation system. Seven and ten months after tralanting, the following parameters were measured; vegetative growth (plant height, node No., leaf No., shoot fresh and dry weights, root fresh and dry weights and etc.), yield, fruits quality. Also mineral composition of fruits, shoots and roots, chemical content and volume of drained out solution were measured. The collected data were analyzed by SAS software, and LSD test (5% level) was applied to compare means. Results showed that highest vegetative growth was produced by perlite (75%) + zeolite (25%), but lowest by rice hull and saw dust. Perlite (75%) + zeolite (25%) produced highest fruit No. and yield while rice hull (100%), saw dust (75%) + zeolite (25%) and rice hull (50%) + saw dust (5o %) produced low fruit fresh weight. Also saw dust (75%) + zeolite (25%) and rice hull (50%) + saw dust (50%) produced lowest fruit number per plant and fruit dry weight. Results also showed that adding zeolite and perlite to rice hull or saw dust increased vegetative growth and yield compared to pure rice hull or saw dust. Highest fruit firmness was obtained from using perlite (100%) whereas lowest firmness was obtained when
