Abstract Introduction Recently, there has been a resurgence of interest in anterior cruciate ligament (ACL) preservation using arthroscopic primary repair for proximal tears. The procedure is less invasive than ACL reconstruction, yet studies assessing the early postoperative course are lacking. The goal of this study was to assess postoperative range of motion (ROM), complications and operative times following primary repair and compare this to the gold standard of ACL reconstruction. Methods A retrospective search was performed for patients undergoing primary repair and reconstruction for isolated ACL injuries. Fifty-two repair patients and 90 reconstruction patients were included. Patients were examined at one week and one, three and six months. Rehabilitation protocol consisted of early ROM and was equal for both groups. Outcomes were compared using independent t-tests and chi-square tests. Results Patients undergoing repair had more ROM than patients undergoing reconstruction at one week (89° ± 18 vs. 61° ± 21, p < 0.01) and one month (125° ± 14 vs. 116° ± 18, p < 0.01) postoperatively. All patients had full ROM at six months. Fewer repair patients had < 90° ROM at one week (23% vs. 84%, p < 0.01), and more repair patients had full ROM at one month (57% vs. 30%, p < 0.01) than reconstruction patients. Treatment of meniscal lesions, but not chondral lesions, influenced ROM. Trends towards fewer complications (2% vs. 9%, p = 0.19) and infections (0% vs. 6%, p = 0.20) were noted following primary repair, and the procedure was significantly shorter. Conclusions Following primary repair, patients had better ROM, and trends towards fewer complications than reconstruction. Primary repair is a safe, brief procedure with early ROM and low complication rates.