A 60-days growth trial was conducted in a flow-through culture system to examine the effects of different dietary vitamin C and iron levels on the growth, hematological and immunological parameters of rainbow trout (Oncorhynchus mykiss) fingerlings (with average initial weight of 5.12 ± 0.02 g). Three levels of vitamin C (150, 200 and 250 mg kg^-1 diet) and iron (5, 7 and 9 mg kg^-1 diet) (as ferrous sulfate) and their combination were used to prepare diets used in nine experimental treatments with three replicates. The results revealed that the supplementation of basal diet with vitamin C and iron significantly affected the final body weight (FBW), total length (TL), feed conversion ratio (FCR) and specific growth rate (SGR). Among the haematological parameters haematocrit and mean corpuscular volume (MCV) were significantly influenced by vitamin C and iron. Results also showed that lysozyme and IgM concentrations significantly changed among dietary treatments. Based on the results of this study, it can be conclude that addition of vitamin C and iron to the basal diet of cultured rainbow trout will improve the growth rate and well-being of this fish.