Oil-in-water nanoemulsions based on vegetable oils have extensive antimicrobial properties against bacteria, viruses, fungi and spores due to their ability to destabilize the lipids in the cell wall of the organism. For this reason, their application has been considered as a way to increase the shelf life of fish during the chilled storage. In the present investigation, the effect of oil-in-water nanoemulsion of sunflower oil on the quality and shelf life of rainbow trout fillet during twelve days of refrigeration storage was investigated. After preparing the fillets, the samples were coated with a sunflower oil nanoemulsion and then refrigerated for twelve days, then at four-day intervals (0- immediately after coating treatment-, 4, 8 and 12 days) were evaluated for some quality indicators (thiobarbituric acid, TBA), total volatile nitrogen, TVB-N; water holding capacity, WHC; & color parameters (including brightness L*, redness a* and yellowness b*). Uncoated fillets were considered as control set. The obtained results showed that coating the fillets with nanoemulsion of sunflower oil had a significant effect on most of the studied indicators (P <0.05) and resulted in better protection of the fillets against spoilage conditions. Therefore, according to the achievements of the present study, it is recommended to cover rainbow trout fillets with sunflower oil nanoemulsion when chilled storage is used to preserve them.