The spawning in Crassostrea madrasensis of Muttukadu Backwater is prolonged from January to November with peaks in February-March and September-October. Female oysters were dominant in several months of the year and males outnumbered females in August and September 1986, February and May 1987. Among the four stations, where oyster spat settlement was studied, Muttukadu Bridge yielded good settlement of spat especially in October. A maximum of 109 oyster spat set on a Urns-coated tile. The fouling organisms and their intensity of settlement on the clutch was recorded. Maturation and spawning of oysters and spatfall were correlated with salinity and temperature.