ABSTRACT The success in anaerobic systems on treatment of medium  and high strength industrial wastewaters encouraged the researchers to study the anaerobic treatment of domestic wastewaters. The aim of this investigation was to observe the treatment potential of domestic wastewaters in the anaerobic upflow sludge blanket reactors (UASBR), determination of hydraulic and kinetic factors affecting the performance of the system and to develop a compact treatment system for the regions of Turkey having a mild and warm climate by using the experimental data of the study. The experimental studies have been performed on an anaerobic upflow sludge blanket reactor for about  one and a half years in laboratory conditions.  Key Words: Anaerobic upflow sludge blanket reactor, Domestic wastewater, Nutrient  removal, Second order substrate removal kinetics.