The loop method permits determining of bacteriuria without the necessity for serial dilution, and with a precision greater than that of the dip inoculum test. Results indicate that the method allows us to establish the level of bacteria present in infected urine (approximately 10(5) germs/ml) quite precisely, and furnishes reliable evaluation of high levels. Due to the small quantity removed by the loop, the possible presence of strong concentrations of chemobiotics does not influence the results, as subinhibiting concentrations easily occur with diffusion.