Free living nematode communities in the Tran De estuary, Soc Trang province was investigated following salinity gradient from river mouth toward inland. Eighty genera, 27 families, 8 orders of 2 dasses Enoplea and Chromadorea were detected. The value of maturity index varied between 2.29 and 3.28. It indicates the ecological conditions of nematode communities are impacted from sea toward inland.