Since the prohibition of phosphates in detergents, a considerable shift of the nutrient ratio P/TOC (phosphorus/organic carbon) in untreated sewage could be observed. The decrease of phosphate concentrations led to an increase of the removal rate in conventional activated sludge plants from 15 % up to 40%, and allows to consider additional biological P-elimination by luxury uptake as feasible treatment process in Switzerland. A literature survey reveals insight into recent research of the microbial processes of phosphate release and uptake and the consequent design considerations for the necessary anaerobic/aerobic activated sludge systems. Experimental results of pilot and full scale plants show in general satisfactory results. The influence of incontrollable nutrient conditions, concerning above all readily biodegradable substances and recycled nitrates, causes, however, instabilities of the process performance. It is therefore doubtful, if the stringent Swiss effluent standards of 0.8 mg P/l could be reached. Additional support by chemical precipitation would be necessary. Although biological phosphate removal offers many advantages compared to chemical precipitation, high investments and additional modifications concerning the water and the sludge handling flow schemes may not favor a wide application.