Background: LATERAL ankle sprains are one of the most common injuries in athletes. However, there is little information about the risk factors of this injury. The aim of the present study was to determine prospectively intrinsic risk factors for LATERAL ankle sprains in athletes. Methods AND materials: A LONGITUDINAL study was carried out on 152 male athletes recruited from clubs in Hamadan province by first completing a personal information registration form at the beginning of the season. Then, their height, weight, body mass index, hip abductor, hip extensor, ankle evertor, AND invertor muscle strength were measured. The participants played AND practiced for 20 months. LATERAL ankle injuries were registered during 20 months AND exposure to sport was recorded. Since the dependent variable was grouped (presence or absence of sprain), logistic regression was used to analyze the data (p≤ 0. 05). Results: A total of 34 new ankle sprain injuries were recorded in total training sessions AND competitions, which was equivalent to 0. 804 injuries per 1000 hours of play AND training. The results of logistic regression showed that AGE (P = 0. 04, OR = 1. 040), height (P = 0. 03, OR = 1. 024), weight (P = 0. 05, OR = 1. 008), body mass index (P = 0. 04, OR = 1. 077), invertor muscles strength (P = 0. 00, OR= 1. 091) ), evertor muscles strength (P = 0. 03, P = 1. 051), AND previous injury history (P = 0. 001, OR=51. 016) are significantly associated with the incidence of ankle sprain injury. According to the results of regression analysis AND ROC curve, the history of previous injury was introduced as the main predictor of ankle sprain. Conclusions: It seems that previous injury history, AGE, height, weight, AND body mass index can predict LATERAL ankle sprain. These results can help coaches AND players prevent this injury in the future.