Our aim was to estimate the prevalence of symptomatic pelvic organ prolapse (POP) in a Swedish urban female population. The cross-sectional study design included 8,000 randomly selected female residents in Stockholm, 30-79-year old. A postal questionnaire enquired about symptomatic POP, using a validated set of five questions, and about urinary incontinence and demographic data. Of 5,489 women providing adequate information, 454 (8.3%, 95% confidence interval 7.3-9.1%) were classified as having symptomatic POP. The prevalence rose with increasing age but leveled off after age 60. In a logistic regression model that disentangled the independent effects, parity emerged as a considerably stronger risk factor than age. There was a ten-fold gradient in prevalence odds of POP with parity, the steepest slope (four-fold) being between nulliparous and primiparous women. The prevalence of frequent stress urinary incontinence was 8.9% and that of frequent urge incontinence 5.9%. Out of the 454 women with prolapse, 37.4% had either or both types of incontinence.