This study was carried out to evaluate the effect of chitosan on chemical, colour, sensory and microbial changes of marinated sardine (Sardina pilchardus) fillets. Marination solution consisted of 10% sodium chloride +1% chitosan (dissolved in 3% acetic acid) for the chitosan group, and 10% sodium chloride +3% acetic acid solution for the control group. After the marination process, sardine fillets were packed and stored at 4 degrees C for 60 days. Thiobarbituric acid (TBA) values were found to be lower in the chitosan group than the control group (P<0.05). There was no difference in the total volatile basic nitrogen (TVB-N) value between groups and this remained low during storage. pH was under 4.5 in both groups during storage. Chitosan had no statistically significant effect on L*, a*, or b* values of marinated sardine fillets. According to sensory analysis, shelf life of the chitosan group was found to be ten days longer than that of the control group. Total bacteria count of two marinated groups was found to be less than 1 log CFU/g. This study concluded that sardine marination with the addition of chitosan can delay undesirable chemical changes, retard lipid oxidation, improve sensory attributes and extend the shelf life of the product during refrigerated storage.