Most people have not returned to their preinjury level of sports participation at 12 months after anterior cruciate ligament (ACL) reconstruction surgery. Twelve months' follow-up may be too early to assess return-to-sport outcomes accurately.This study was undertaken to evaluate the medium-term return-to-sport outcomes after ACL reconstruction surgery.Case series; Level of evidence, 3.A self-report questionnaire was used to collect data at 2 to 7 years after ACL reconstruction surgery regarding preinjury sports participation, postoperative sports participation, and subjective knee function. The main inclusion criteria were participation in regular sports activity before injury and the attendance at routine surgical follow-up appointments.A total of 314 participants (mean age, 32.5 ± 10.2 years) were included at a mean 39.6 ± 13.8 months after ACL reconstruction surgery. At follow-up, 45% were playing sport at their preinjury level and 29% were playing competitive sport. Ninety-three percent of the study sample had attempted sport at some time after their ACL reconstruction surgery. Those who had not attempted their preinjury level of sport by 12 months after surgery were just as likely to have returned to preinjury level by 39 months after surgery as those who had played sport by 12 months (risk ratio, 1.1; 95% confidence interval, 0.76-1.6).Less than 50% of the study sample had returned to playing sport at their preinjury level or returned to participating in competitive sport when surveyed at 2 to 7 years after ACL reconstruction surgery. Return to the preinjury level of sport at 12 months after surgery was not predictive of participation at the preinjury level in the medium term, which suggests that people who return to sport within 12 months may not maintain their sports participation.