Seventy patients with unilateral primary anterior cruciate ligament (ACL) injuies were randomized into receiving an acute or delayed anterior cruciate ligament reconstruction (ACLR). An early ACLR was defined as a reconstruction performed within 8 days from sustaining an injury, whereas a delayed ACLR was performed within 6 to 10 weeks from injury. The primary outcome of interest was the total number of sick-leave days taken after an acute or delayed ACLR. Secondary outcomes of interest included the following patient-reported measures: International Knee Documentation Centre (IKDC), Knee Injury and Osteoarthritis Outcome Score (KOOS), Lysholm and Tegner activity scores, range of motion, thigh circumference, knee laxity scores, and one-leg hop test scores. IDKC scores, Lysholm scores and Tegner scores were measured at 6 months and 12 months post-operation. All remaining outcomes were measured at 1 year post-operation. Results revealed that the acute ACLR group used significantly less mean sick-leave days compared to the delayed ACLR. Moreover, the acute ACLR group had significantly favourable range of motion in flexion compared to the delayed ACLR group. All remaining outcomes were similar between the 2 treatment arms.