INTRODUCTION: Decompression sickness (DCS) can occur during unpressurized flight to altitudes >18,000 ft (FL180; 5486 m). To our knowledge, this has not been studied in general aviation (GA). This knowledge gap may have public health and safety implications because the most popular models of GA aircraft by sales volume are capable of flying >FL180.METHODS: Data from a 1-yr period in a commercial flight tracking database were analyzed to identify flights >FL180 in unpressurized, piston aircraft in the United States. Peak altitude and duration at that altitude were used to calculate DCS risk employing the U.S. Air Force (USAF) Altitude Decompression Sickness Risk Assessment Computer (ADRAC). Registration numbers were cross referenced in publicly available federal databases to identify any events that might be attributable to impairment due to DCS. A web-based survey of practices and associated symptoms was also made available to GA pilots through an online discussion forum.RESULTS: During the data collection period, 1696 flights occurred. The DCS risk was calculated to be 1.9 4.2%. There were 42 responses to the survey. Of these, 25 (59.5%) pilots reported having flown at altitudes >FL180 and 21 (84%) of them reported symptoms possibly attributable to DCS. None sought medical attention. No safety events were identified for any of the aircraft during the study period.CONCLUSION: The risk of DCS in the GA community is not zero. As GA aircraft performance profiles advance and sales increase, this may have significant implications from a public health and safety perspective. Further study is warranted.Harrison MF, Butler WP, Murad MH, Toups GN. Decompression sickness risk assessment and awareness in general aviation. Aerosp Med Hum Perform. 2021; 92(3):138145.