Singers have reported higher prevalence of vocally harmful behaviors, vocal symptoms, and voice disorders than nonsingers have. The purpose of this study was to investigate the prevalence of voice disorders among choir singers and to discover the risk factors associated with voice disorders. Another purpose was to explore the choir singers' knowledge about the anatomy and physiology of the voice, and voice ergonomics.Three hundred and fifteen adult choir singers, 65% women, and 35% men, completed a web-questionnaire. The questionnaire included demographic questions and questions about vocal symptoms, risk factors for voice disorders, and voice knowledge.Twenty one percent of the participants experienced two or more frequently occurring vocal symptoms, which was defined as having a functional voice disorder. Choir singers with a vocally demanding profession were almost twice as likely to report several frequently occurring vocal symptoms. Health-related risk factors, such as inhalant allergy and asthma, had a significant relation with the number of vocal symptoms. The overall voice knowledge among the choir singers seemed limited.The prevalence of voice disorders among choir singers seems to be similar to the prevalence rate among professional voice users. Choir singers with a vocally demanding profession are at a higher risk of developing a functional voice disorder. The results of this study raise the importance of educating choir singers about the voice, in order to prevent development of voice disorders.