OBJECTIVE To evaluate the accuracy and diagnostic usefulness of a disposable flowmeter consisting of a plastic funnel with a spout divided into three chambers. METHODS Men with lower urinary tract symptoms (LUTS) voided sequentially into a standard flowmeter and the funnel device recording maximum flow rate (Q(max)) and voided volume (V(void)). The device was precalibrated such that filling of the bottom, middle and top chambers categorized maximum input flows as <10, 10-15 and > 15 ml s(-1) respectively. Subjects who agreed to use the funnel device at home obtained readings of flow category and V(void) twice daily for seven days. RESULTS A single office reading in 46 men using the device showed good agreement with standard measurement of Q(max) for V(void) > 150 ml (Kappa = 0.68). All 14 men whose void reached the top chamber had standard Q(max) > 15 ml s(-1) (PPV = 100%, NPV = 72%) whilst eight of 12 men whose void remained in the bottom chamber had standard Q(max) < 10 ml s(-1) (PPV = 70%, NPV = 94%). During multiple home use by 14 men the device showed moderate repeatability (Kappa = 0.58) and correctly categorized Q(max) in comparison to standard measurement for 12 (87%) men. CONCLUSIONS This study suggests that the device has sufficient accuracy and reliability for initial flow rate assessment in men with LUTS. The device can provide a single measurement or alternatively multiple home measurements to categorize men with Q(max) < 15 ml s(-1).