A device for measuring the peak flow rate of a urine discharge comprising, a hollow receptacle having a chamber, an inlet port for passage of the discharge into the chamber, and an outlet port for passage of the discharge from the chamber at a predetermined flow rate. The device has a collection container having a closed bottom, a cavity, and an opening adjacent an upper end of the container. The receptacle has an aperture in a lower wall of the receptacle to removably receive the container with the container opening located a predetermined height above the receptacle lower wall in the chamber, such that the discharge passes from the chamber into the container cavity at a predetermined height of the liquid in the receptacle chamber.