Post-harvesting, handling and storage practices, particularly during the summer months, are crucial for mussel farms, as they induce stress, mortalities and affect overall performance and marketability. In the current work, Mediterranean farmed mussels, were stored into plastic net bags of different weights (7.5kg, 10 kg, 12.5 kg and 15 kg) and reimmersed into the farm sea water during summer 2012. The experiment was conducted under warm summer conditions in Mediterranean waters with temperature levels close to the upper tolerance limits of the mussels (28 degrees C). Mortality rates and condition index (CI) were calculated in all mussel bags at four sampling dates over a 46 days period. It is concluded that mussels graded-packed on bags (7.5-15 kg) could be preserved underwater for 25 days of re-immersion without significant mortality and CI losses.