Nisin is a natural antimicrobial and has inhibitory effect on the pathogens and spoilage organisms. The purpose of this study was to evaluate the effects of nisin (0.15%) and sodium acetate (1%) individually and in combination on shelf life of vacuumed trout (whole fish without viscera) in refrigerated temperature. Physical and chemical parameters including pH, peroxide value, thiobarbituric acid and total volatile nitrogen bases and bacterial factors such as TVC, PTC and LAB were examined. These parameters were measured at an interval of 4 days for 16 days.  Results showed that the PV, TBA, TVN and pH in combination of sodium acetate and nisin Z treatments were significantly lower compared to control (no preservatives) (P<0.05). Treatments with sodium acetate and nisin Z (individual) were followed after combination treatment. It seems that a combination of natural and chemical preservatives significantly increases shelf life of rainbow trout.