Study of coastal water quality plays important role in evaluating and determining the pollution status and health of the water. Ulhas river estuary is one of the important water bodies in Thane district. Entire stretch of estuary was arbitrarily divided into three zones. Physical and chemical variables of water were monitored month-wise in the year 2004-2005. In the present study the entire stretch of estuary showed high values of BOD, PO4-P, NO3-N, Suspended solids and hypoxia suggesting deterioration of the estuary.