The quality of natural waters can be seriously affected by both point and not-point pollution sources such as industrial discharges, agricultural activities, water withdrawal, drought, and floods.Buyuk Menderes River Basin in Turkey is subjected to these factors. It is required to evaluate its water quality for sustainable surface water management. The European Commission Water Framework Directive (WFD) was constructed to monitor water quality for rivers, lakes and transitional and coastal waters utilizing networks. Countries evaluated the Water Framework Directive and principles of WFD have been adapted to the legislation of the country over the past eighteen years. Therefore, this study was conducted in Buyuk Menderes River Basin to determine its water quality classes according to the Republic of Turkey Ministry of Forestry and Water Affairs' Regulation (WAR) for Management of Surface Water. Seasonal samples were collected from 39 surveillance monitoring stations. The parameters monitored stated in the regulation were physical ones as temperature, pH, COD and BOD, nutrient parameters, etc. Annual averages of the monitored physico-chemical pollution parameters were used to determine the water quality classes of stations and the whole river basin. The results indicated that the water quality of Buyuk Menderes River Basin was either class III or class IV. Besides, the water quality of Buyuk Menderes River Basin was presented based on Water Framework Directive. So, two regulations (WAR and WFD) were compared with each other according to water quality classification.