Uroflowmetry, the simple, non-invasive measurement of urine flow over time during micturition, has a long and interesting history, clear definitions, a clear purpose in screening for voiding difficulty and, most importantly, technical accuracy. Data interpretation is currently limiting its clinical utility, despite appropriate analysis being available in long-standing existing research. The main clinically important numerical parameters are the maximum and average urine flow rates and the voided volume. Urine flow rates are strongly dependent on voided volume. Reference to established (Liverpool) nomograms will most accurately correct for this dependency. Nomograms will also optimise the validation of uroflowmetry data and the accurate assessment of its normality, compared with fixed urine flow rates and "cutoffs" for voided volume. Abnormally slow urine flow (under the 10th centile Liverpool Nomograms) is the most clinically significant abnormality. Repeat uroflowmetry, concomitant post-void residual measurement and voiding cystometry studies are appropriate options for evaluating any abnormal uroflowmetry.