This study investigated the changes in quality of pasteurized mussels during storage at 4 degrees C +/- 1 degrees C. Mussels (Mytilus galloprovincialis) were harvested from the Marmara Sea in March. The mussel flesh was packed with lemon juice, apple vinegar, finely chopped onion, salt, and black pepper. Then, all the packets were pasteurized (at 70 degrees C for 8 min) and stored for 21 days at 4 degrees C +/- 1 degrees C. Results showed that the contents of protein, fat, and ash of pasteurized mussels were significantly higher (p<0.05) than those of raw samples. The moisture content of mussels was significantly decreased (p<0.05) after heat treatment. The meat yield of pasteurized mussels was 10.42%. Sensory evaluation results indicated that the acceptability of pasteurized mussels at refrigerated storage was limited to 9 days. The TVB-N value of pasteurized samples exceeded the acceptability limit of 22-25 mg/100 g on the 9th day. The TMA-N amount of pasteurized mussels remained lower than the acceptability limit during storage. The initial microbial load of the mussel samples reduced after the pasteurization process. This reduction was observed in the total mesophilic and psychrophilic bacterial count, with the yeast mold counts after pasteurization being 2.44, 2.07, and 2.37 log cfu/g, respectively.