Studies on transplantation of oysters in Mulky estuary was carried out from January 2010 to May 2010. The assemblages of macrobenthos with the transplanted oyster were recorded. The assemblages of macrobenthos increased gradually over the months. Overall, the population density and species of macrobenthos with transplanted oysters varied from 36 to 86No/m². Minimum number of macrobenthos was recorded during February 2010 and maximum during April and May 2010. The survival rate of transplanted oysters varied between 86.60 and 100%. The environmental factors such as the water temperature, sediment temperature, salinity, DO, pH, sedimentation rate, phytoplankton wet weight and sediment organic carbon varied from 29.89 to 34.45ºC, 31.60 to 35.20ºC, 24.20 to 33.62ppt, 4.69 to 4.85mg/l, 7.18 to 7.8, 0.28 to 1.33g/m²/month, 8.86 to 58.47 mg/m³ and 0.02 to 0.24% respectively