The efficiency of the polycarbamate membrane filtration technique for detecting Schistosoma haematobium eggs in urine has been increased by using a pore size of 14 micrometers diameter and the suction of a water jet pump. The technique permits filtration of several 1000 ml of urine in one test. Eggs concentrations of 1 egg in more than 1000 ml of urine were detected. Viability was assess after filtration by staining with trypan blue. Preliminary data of 118 Schistosoma haematobium-positive urine samples of 32 patients suggest that the filtration trypan blue-staining-technique is of high validity in light infection with scanty egg-output.