Background and purpose: This nationwide questionnaire survey was performed to clarify the prevalence of groin pain in unicycle athletes and to reveal the relationship between groin pain and factors such as age or athletic career. Patients and methods: To evaluate the prevalence of groin pain, the questionnaire was sent to 1304 unicyclists belonging to the Japan Unicycle Association. All subjects aged 6 years or older at the time they answered the questionnaire. Results: Overall, 17% of unicyclists complained of groin pain. Pain was more common in those aged 13–19 years and in those with a career lasting more than 6 years. Conclusion: The incidence of groin pain (17%) among unicyclists is higher than that among athletes participating in other sports. Unicyclists aged between 13 and 19 years old and those with an athletic career of more than 6 years often suffer from groin pain.