Fresh chub mackerel (Scomber japonicus Houttuyn 1780) fillets were treated with either 0%, 2% or 4% lactic acid solutions, packaged under vacuum, and stored at 4 degreesC for 12 days. Sensory, chemical, and microbiological analyses were done every 3 days. The control group (0% lactic acid) spoiled after 9 days of storage. The shelf-life of refrigerated fillets increased when they were dipped in acid and these fillets spoiled at the 12th day of storage. It was determined that using lactic acid increased the shelf-life of vacuum-packaged chub mackerel.