Distribution, abundance and biodiversity of macrobenthic standing stock in the nearshore coastal system of Bombay, Maharashtra, India were estimated (1985-86) in relation to the prevailing environmental stress due to disposal of anthropogenic wastes. Selected water quality parameters like S ppt, DO, BOD, nutrients etc. were monitored. Macrobenthos and water quality of the Harbour-Thana creek-System (HTS) and the Bassein creek-coastal system (BCS) were studied and compared. HTS sustained relatively higher macrofaunal abundance and biodiversity as compared to BCS. An increase in faunal group diversity as well as species diversity of polychaetes from the inner creek to the open coastal zone was noticed. Sediment texture and organic matter were correlated with macrofaunal standing stock. A pollution induced ecological modification of macrobenthos especially in the inner creek regions of Thana and Bassein was evident.