The present work was undertaken to examine the effect of chitosan and rosemary in extending the shelf life of refrigerated Nile tilapia(orechromis niloticus)  fillets .
Three different treatments ( chitosan “C" , rosemary “R" , a mix of them “C+R" ) beside the control were prepared . Chitosan solution was prepared at 1.5% (w/v) in 1% v/v acetic acid. Rosemary solution was prepared as the chitosan solution . The mix of chitosan and rosemary solution was prepared with 1% (w/v) chitosan  with 1% (w/v) rosmary  in 1% v/v acetic acid following the same procedure of chitosan preparation. The samples were coated and stored at ( 4 ± 1 ^oC ) for 15 days and sampling was done periodically at 0, 3, 6, 9, 12, 15 days. Microbiological , chemical and sensory attributes were periodically assessed . The results indicated that the three pretreatments could more effectively maintain quality and could extend the shelf life by 3­ 6 days compared to the control group during refrigerated storage.