Kucuk Menderes river deltaic zone is the most important wetland in the Western part of Turkey. Water and sediment quality parameters were collected monthly from May 2003 through April 2004 at six stations. pH, conductivity, temperature, dissolved oxygen, nutrients (Nitrate-nitrogen, ammonium-nitrogen, phosphate-phosphorus) and chlorophyll a were measured in water column Cu, Zn, Mn, Cd, Cr, Ni and Pb were investigated in sediment samples. A large spatial and temporal variability in dissolved oxygen was identified which can probably be related seasonal effects, specification of river and anthropogenic impacts. Kucuk Menderes river deltaic zone was found first quality in terms of nitrate concentrations but third quality for ammonium and dissolved oxygen levels according to Turkish regulation of quality criteria for the freshwater resources. The major factors influencing the nutrients are suggested to be agricultural runoff and domestic sewage. Metal concentrations found in this study were compared with the sediment quality guidelines for freshwater ecosystem. The concentrations of Cr, Ni, Zn, Cu and Mn were above the threshold effects levels especially in station 4 (Belevi bridge) because of industrial and agricultural activities.