Introduction: Injuries to the hip, groin, and thigh are prevalent in adult Gaelic footballers and hurlers, but the incidence of injury in adolescent and collegiate players has not been established. Methods: Adolescent (n=292, 15.76±0.8 years) and collegiate (n=342,19.4 6±1.9 years) Gaelic footballers and hurlers took part in a 1-year prospective epidemiological study. Any injury sustained during training or competition resulting in restricted performance or time lost from play was assessed weekly by an athletic rehabilitation therapist. An injury report form was completed to ensure standardisation of the injury description. Results: The hip/groin/thigh was the most common region of injury in adolescent (25%) and collegiate (35%) players, accounting for 1.4 and 5.4 injuries/1,000 hours in adolescents and collegiate players, respectively. The hamstring (9.6%, 16.1%), pelvis and groin (8.8%, 7.3%), quadriceps (6.4%, 7.3%), and hip (3.2%, 6.2%) accounted for a large proportion of injuries in adolescent and collegiate players, respectively. Strains (54.3%, 65.3%) and contusions (14.3%, 20.8%) were the most common. Noncontact injuries predominated (82.9%, 77.8%), with sprinting the most common mechanism of injury (65.7%, 47.2%). Injuries during tackling occurred more frequently in collegiate players (28.1%) than adolescents (5.7%). Injuries primarily occurred in the 4th quarter in collegiate players (64.6%). Injuries occurred more frequently at the beginning of the calendar year, dropped significantly over the summer months, and increased again nearing the end of the year. A similar percentage of minor (33.8%), moderate (35.2%), and severe (31.0%) injuries occurred in collegiate players; however, severe (43.8%) injuries primarily occurred in adolescents, followed by minor (34.4%) and moderate (21.9%) injuries. Conclusions: Injuries to the hip/groin/thigh are common in adolescent and collegiate Gaelic footballers and hurlers. This study paves the way for injury prevention strategies in these populations.