Both the protection of sustainable aquaculture sources and production of low cost fish feeds via usmg of alternative cheaper protein sources instead of fish meal is one of the most important aims of feed producers. Soybean and soybean products are the most attractive feed stuffs in finfish feeds for these reasons. In this study, low (15%) and high (70%) levels of fullfat soybean meal in rainbow trout feeds were used and growth performance, feed consumption, feed conversion ratio and production cost of rainbow trout were investigated. The average live weight of 300 rainbow trout (Oncorhynchus mykiss) used in this experiment was 49.73±0.56 g. Two trial groups which were fed rations containing low and high levels of full fat soybean meal were formed. There were 3 replications for each treatment and the trial lasted I C) weeks. Experimental diets were prepared as isonitrogenous (42% CP) and isocaloric (14.65 MJ DE kg —I feed). At the encl of trial, there was no significant difference among the groups in terms of live weight, live weight gain and body composition except fat content (13>0.05) however, significant differences for feed consumption and feed conversion ratio between the groups were observed (p<O.05). Consequently, it is concluded that the fish fed with complete feed containing high level full fat soybean meal could be produced cheaper without any negative effect (P<0.05).