A retrospective evaluation of flowmetry as single urodynamic technique in the diagnosis of lower urinary tract obstruction was performed in 130 male patients. A statistically significant difference was observed for maximum urinary flow minus mean urinary flow in the presence of obstruction. Analysis of the morphology of the flowmetry curve could orient the diagnosis of the underlying condition. Measurement of post-micturitional residual urine appears to have no statistical value. The detrusor pressure/urinary flow test continues to be the most reliable in the diagnosis of male lower urinary tract obstruction.