ABSTRACT: Background:Fly-fishing requires rhythmic, coordinated movements to successfully cast a fly line. Previous studies have shown that the biomechanical demands of fly-casting may cause some individuals to develop upper extremity pain or injuries. Purpose:To report the rates, trends, and contributing factors of upper extremity pain and overuse injuries in a sample of North American recreational fly-fishers. Study Design:Descriptive epidemiology study. Methods:Participants were reached via 3 popular online fly-fishing forums in April 2019. Each consenting North American participant over 18 years of age was given a link to a unique survey that recorded his or her demographic and orthopaedic histories, fly-fishing experience, equipment, casting techniques, upper extremity pain after fly-fishing, and chronic outcomes. Results:The 162 fly-fishers included were 63.3 (± 11.5) years of age, and 95.1% were men. In total, 59 (36.4%) reported experiencing upper extremity pain immediately after fly-fishing. Pain was rated a 4.0 (interquartile range, 3.0-6.0) on a 10-point Likert scale, commonly lasting less than 1 day (45.0%) or between 1 day and 1 week (45.0%). The majority (62.7%) reported not needing to see a medical provider for their pain/soreness. Those who did most commonly received diagnoses of elbow or rotator cuff tendinitis. Pain/soreness was associated with casting in an elliptical/sidearm fashion, compared with overhead or 2-handed casting (P = .006) using a weighted line or added weight (split-shot, weighted heads, etc) (P = .034) and with grip styles where the hand was pronated compared with being in a more neutral position (P = .046). The mean shortened version of the Disabilities of the Arm, Shoulder and Hand score was 10.8 (± 11.5). Higher scores were associated with a history of self-reported upper extremity orthopaedic injuries (B = 6.059 [95% CI, 2.476-9.642]; SE, 1.814; P = .001) and having had surgery for these injuries (B = 8.484 [95% CI, 4.454-12.513]; SE, 0.314; P < .001). Conclusion:In this sample of recreational fly-fishers, no aspects of fly-fishing were associated with long-term upper extremity disability, and only a little more than a third reported having transient pain immediately after fishing. Casting style, using weighted lines or added weight, and grip style were all associated with pain. These are modifiable risk factors that can be adjusted to reduce the risk of upper extremity pain immediately after fly-fishing.