Background:Incidence and risk factors of parachute injuries has been studied in developed countries,but not in trainees of the airborne forces in the Royal Thailand Army.Methods:A prospective cohort study was conducted among 992 military personnel who attended the basic airborne training program from February to July 2018.Information sheets were used to collect data about(a)personal demographics;(b)environmental conditions surrounding the parachute practice;and(c)parachute-related injuries.The incidence rate of injury was then calculated.Risk factors were examined using multilevel Poisson regression analysis and presented as incidence rate ratio(IRR)and 95％confidence interval(95％CI).Results:A total of 166 parachute-related injuries occurred in 4677 jumps.The incidence rate of injury was 35.50 per 1000 jumps(95％CI 30.04-41.21).Factors significantly related to parachute injury included:jumping with equipment versus without equipment[adjusted IRR(95％CI):1.28(0.88-1.87)],higher wind speed[1.54(1.27-1.87)per knot],airplane versus helicopter exit[1.75(0.68-4.55)],side versus rear exit[2.13(1.43-3.23)],night versus day jumping[2.19(0.81-5.90)],and presence of motion sickness[3.43(1.93-6.92)].Conclusions:To prevent military static line parachute injuries,the following factors should be taken into consideration:type of aircraft,aircraft exit,time of the day,equipment,motion sickness and wind speed.Trial registration:The project was certified by the Research Ethics Committee,Faculty of Medicine,Chulalongkorn University(IRB No.697/60).