Objectives: To evaluate the prevalence of urinary stress incontinence (USI) in menstruating women practicing recreational sport activity, to detect specific sports with a stronger association with UI, and to evaluate risk factors possibly related to this condition. Design: Epidemiological study Setting: Non competitive sport organizations in the province of Varese - Italy. Participants: 679 women in fertile age, practicing recreational sport activity. Intervention: Anonymous questionnaire on UI. Main outcome measurements: The questionnaire included questions about patients’ general characteristics, occurrence of UI in relation to sport or daily general activities, time of onset of this condition, frequency of leakage episodes, correlation of incontinence with types of movements or sports, subjective impression of being limited in such occasions and/or necessity to modify the type of sport. Results: UI was reported by 101 women (14.9%). Of them, 32 (31.7%) complained of UI only during sport activity, 48 (47.5%) only during daily life and 21 (20.8%) in both circumstances. BMI and parity were significantly associated with the risk of urinary incontinence. Looking at the different sport activities, the higher rate of incontinent women was found in basketball (16.6%), athletics (15%), and tennis or squash (11%). 10.4% of women abandoned their favourite sport, due to stress UI, and a further 20% limited the way they practiced their favourite sport to reduce leakage episodes. Conclusions: Female UI affects a relevant proportion of young women practicing non-competitive sport activity; it can cause abandon of the type of sport or limitation in its practice.