OBJECTIVE To determine differences between vaginally parous and nulliparous women presenting with urinary incontinence and pelvic organ prolapse. METHODS Seven hundred forty eight consecutive referrals with urinary incontinence or pelvic organ prolapse, 62 of whom were nulliparous, were included in the analysis. Five hundred thirty-seven (72%) had urinary incontinence and 235 (31%) had at least stage III pelvic organ prolapse. Each subject had standard history, physical examination, and multichannel urodynamic testing. Differences between parous and nulliparous women were compared using parametric and nonparametric analysis of variance and the chi2 test with Yates correction where appropriate. RESULTS The only significant demographic difference between the groups was that parous women had more previous continence and prolapse surgery. There were significant differences in distribution of diagnoses according to parity, with the nulliparas much less likely to have pelvic organ prolapse. Among incontinent women without prolapse, nulliparas were significantly more likely to have pure detrusor instability. Of those with pure genuine stress incontinence, nulliparas were older, had less anterior vaginal wall descent, less bladder neck mobility, narrower genital hiatus and perineal body measurements, and lower maximum urethral closure pressures. Of those with pure detrusor instability, the only difference was that nulliparas were significantly younger. For women with stage III pelvic organ prolapse or worse, no significant difference in any measured characteristic was noted. CONCLUSIONS Nulliparous women were less likely to present with pelvic organ prolapse and those with urinary incontinence differed little from incontinent parous women.