BACKGROUND: Replacement of natural materials with syntheticdrugs in order to increase production and safety. OBJECTIVE: The purposeof this study was to investigate the effect of feed supplemented with ginger (Zingiberofficinale) extract on the growth, biochemical and hemato-immunologicalparameters of rainbow trout (Oncorhynchus mykiss). METHODS: Fishwith an average body weight 14.1±0.2 g were fed diet for 8 weeks with 0.5% and1% ginger extract and with unsupplemented commercial diet as the control. Bloodsamples were collected from caudal vein from apparently healthy fish at the endof trial. Growth (weight gain, specific growth ratio and condition factor),hematological (RBC,WBC, Hb, Hct, monocyte, lymphocyte and neutrophil),Biochemical (glucose, total protein, triglycerides, cholesterol, albumin, AST,ALT, LDH and ALP) and immunological (lysozym activity, ACH50,IgM, and SOD)parameters were determined. RESULTS: The results showed that there wereno significant differences (p>0.05) in growth, hematological, biochemicaland metabolic enzymes between fish fed control and ginger extractsupplementation. The lowest level of cortisol was observed in 0.5% gingerextract (p<0.05). Lysozyme activity was significantly increased in 0.5%ginger extract fed fish (p<0.05). CONCLUSIONS: The results suggestthat by using 0.5% ginger extract there will be an improvement in growth andimmune function of rainbow trout