Spoilage of fish muscle results from changes brought about by biological reactions such as oxidation of lipids,reactions due to activities of the fish’s own enzymes,and the metabolic activities of microorganisms.  These activities lead to a short shelf life in fish and other seafood products. Propolis is a natural product derived from plant resins collected by honeybees.  Propolis has been used in traditional medicine for centuries.  It is known that propolis possesses anti- microbial, antioxidative,  anti-ulcer and anti-tumor activities. At this study biochemical and microbiological parameters of rainbow trout(Oncorhynchus mykiss) treated to 10% concentration of  alcoholic extraction of Kurdistan propolis for 24 days were determined.  Analyses were carried out for mesophilic and psychrophile bacteria counting as microbiological parameters and total volatile base nitrogen (TVBN), Thiobarbituric acid reactive species(TBARS), pH and acidity as biochemical parameters, for 0, 8, 16 and 24 days of storage at 4 ºC with vacuum packaging.  The results presented that decreasing in microbiological parameters at control samples were more faster than treated samples and TVB-N,TBARS and acidity of control samples were higher than treated samples and pH of treated samples were higher than control samples after 24 days.  The results suggest that 10% concentration of alcoholic extraction of Kurdistan propolis can enhance the shelf life of rainbow trout fillets during the refrigerated, vacuum packed preservation.