Uroflowmeter has been well documented as an indispensible tool in lower urinary tract diagnosis. In this study 145 normal urinary flow curves in 36 healthy adult males were analysed using the Male Uroflow Diagnostic Interpretation (MUDI) of the DISA urological investigation system. In MUDI, the flow rate pattern is analysed and quantified by previously defined parameters. Then the computed values of these parameters are compared with the values observed in healthy subjects. Finally, the results are conveniently presented on an output sheet. One of the newly defined parameters, (dL/dT) 40, i.e., the bladder contraction velocity at 40 ml before the end of micturition, was situated within the range of 12.5 to 28.3 mm/sec (20.4 +/- 3.9 mm/sec) in healthy males. The variable (dL/dT) 40 did not depend on voided volume and provided excellent discrimination between the control group of healthy males and the group of patients with dysuria. MUDI improves the faults of previous uroflowmetry systems and provides (dL/dT) 40 by which micturition patterns can be discriminated to be good and bad ones. So MUDI seems to be quite versatile in daily urological clinics.