The macro benthos of the Buckingham Canal one of the backwaters of Coleroon Estuary in relation to sediment, organic carbon and environmental variables such as temperature, salinity and dissolved oxygen were studied for a period of one year at two stations. A rich population was found to occur at moderate salinity (14 %„ to 17%o) in post monsoon when the sediment compositions was silty-sand (53-43 %) in nature. The abundance of macro benthos was directly correlated with salinity, silt, clay and organic carbon. A poor macro benthic population was recorded during monsoon and summer periods.