Aims: The aim of our study was to analyze whether uroflowmetry parameters are helpful in diagnosing overactive bladder (OAB). The working hypothesis was that the flow curves of patients with OAB symptoms would appear as a sharp peak flow rate with a short duration and high amplitude, lasting only for a short period during urgency sensation, followed by reduced urine flow. We introduced a new parameter called flow index (FI) defined as an average divided by maximal urine flow rates as a potential marker for diagnosing OAB. Methods: We conducted a retrospective study analyzing 757 urodynamic studies performed in women with lower urinary tract symptoms between 2007-2014. Based on subjective clinical symptoms patients were divided into four groups (pure OAB, mixed urinary incontinence with predominant OAB [MUI-OAB], mixed urinary incontinence with predominant SUI [MUI-SUI], and pure SUI patients). Results: When comparing FI between pure OAB and pure SUI patients, a strong statistically significant difference was found (mean 0.45 +/- 0.08 vs. 0.53 +/- 0.09, respectively; P<0.001). Similar results were found when comparing the patients with pure OAB and MUI-OAB versus patients with pure SUI and MUI-SUI (mean 0.47 +/- 0.11 vs. 0.53 +/- 0.09, respectively; P0.5). Conclusions: FI may be used as an additional marker for OAB diagnosis. (C) 2015 Wiley Periodicals, Inc.