Growth and survival of flat oyster, Ostrea edulis, juveniles of different sizes (15 mm, 20 mm, 25 mm, 30 mm, 35 mm and 40 mm) from natural spatfall were studied in suspended culture in Mersin Bay Izmir, Turkey from April 2002 to August 2003. Environmental parameters such as temperature, salinity, chlorophyll-a, total particulate matter (TPM), pH were monitored each sampling time. Temperature was between 13.8 degrees C (December 2002) and 24.5 degrees C (July and August 2002). Average chlorophyll-a, TPM and pH were 1.7 +/- 0.64 mu g l(-1), 0.01311+/-0.00224 mg l(-1) and 7.65+/-0.22, respectively. Shell length increment for each size groups (from small to large) was determined as 49.99, 43.39, 39.10, 33.11, 39.36 and 25.67 mm, respectively. The smallest group was growth faster than others (P < 0.05). Significant differences in survival rates between size groups occurred (highest: 60% for 15.mm and lowest: 12.8% for 35 mm) (P < 0.05). Condition index and meat yield which showed many variations throughout the study changed from 2.65% to 5.11% and from 6.65% to 12%, respectively.