Diagnostic questions about stress and urge incontinence were validated against a final diagnosis made by a gynecologist after urodynamic evaluation. Thereafter, an epidemiological survey was performed, using similar questions, and correcting the answers for lack of validity. Included were 250 incontinent women at the out-patient clinic and 535 women who reported incontinence in the epidemiological survey. The sensitivity for stress incontinence was 0.66 (95% confidence interval +/- 0.08), specificity 0.88 (+/- 0.06). The corresponding values for urge incontinence were 0.56 (+/- 0.15) and 0.96 (+/- 0.03), and for mixed incontinence 0.84 (+/- 0.10) and 0.66 (+/- 0.07). Using these indices of validity as corrective measures for the diagnostic distribution reported in the epidemiological survey, the percentage of stress incontinence increased from 51 to 77%, while mixed incontinence was reduced from 39 to 11%. Pure urge incontinence increased from 10 to 12%. Mixed incontinence will be overreported in epidemiological surveys. Correction for validity indicates that a larger majority than hitherto reported may have pure stress incontinence.