STUDY DESIGN:Prospective cohort. BACKGROUND:Hip and groin injuries are a significant cause of time lost from training and competition in elite soccer. OBJECTIVES:To explore the association between pre-season assessments of 1) isometric hip adductor and abductor strength using a novel field-test; and 2) the Copenhagen Hip and Groin Outcome Score (HAGOS), and subsequent hip/groin injury in professional male soccer players. METHODS:In total, 204 elite male soccer players from ten professional Hyundai A-League and English Championship League clubs had assessments of hip adductor and abductor strength and completed the HAGOS in the 2017-18 pre-season. In-season hip/groin injuries were reported by team medical staff. Data reduction was conducted using principal component analysis. The principal component for HAGOS and three principal components for strength and imbalance measures were entered with age and prior hip/groin injury into a multivariable logistic regression model to determine their association with prospectively occurring hip/groin injury. RESULTS:Twenty-four players suffered at least one hip/groin injury throughout the 2017-18 season. The principal component for between-limb abduction imbalance (peak strength in the preferred [kicking] limb - non-preferred limb) (OR = 0.58, 95% CI = 0.38 to 0.90, p = 0.011), the principal component for peak adduction and abduction strength (OR = 0.71, 95% CI = 0.50 to 1.00, p=0.045), and the principal component for HAGOS (OR = 0.77, 95% CI = 0.62 to 0.96, p = 0.022), were independently associated with a reduced risk of future hip/groin injury. Receiver operator curve analysis of the whole model revealed an area under the curve of 0.76, which indicates a fair combined sensitivity and specificity of the included variables but an inability to correctly identify all subsequently injured players. CONCLUSION:Hip abduction imbalance, favouring the preferred kicking limb, higher levels of hip adductor and abductor strength, and superior HAGOS values, were associated with a reduced likelihood of future hip/groin injury in professional soccer players. J Orthop Sports Phys Ther, Epub 17 Sep 2019. doi:10.2519/jospt.2020.9022.