Assessment of the residual post-micturition urine is considered by many urologists an important examination in patients with benign prostate hyperplasia. The residue is found in these patients more frequently than in the healthy population. However, it does not always correlate with the uroflowmetric findings. Following analysis of results of urodynamic studies in 315 selected patients with isolated benign prostate hyperplasia the author concludes that the finding of a significant amount of post-micturition residual urine draws the clinician's attention to impaired micturition but does not define the type of disorder nor its grade. It is of importance only in isolated benign prostate hyperplasia, if higher than 100 ml.