Arthroscopic anterior cruciate ligament (ACL) reconstruction has evolved to become a reasonably safe surgery. Nonetheless, complications are inevitable, as with any other procedure, and can adversely impact the outcome. Pre-operative considerations like errors in diagnosis, missing concomitant injuries, or mistiming the surgery can all have adverse effects. Intra-operative complications may be either graft-related or technical. These include complications of graft harvest, preparation, sizing, passage, or fixation. Technical errors may be malpositioned femoral or tibial tunnels or undesirable events during tunnel drilling. Malpositioned tunnels are the most common cause of non-traumatic ACL failure, often requiring revision surgery. Post-operative complications have usually their genesis in the intra-operative period. Infection is the most dreaded of these and may require prolonged antimicrobial therapy, re-admission, or re-surgery. Complications due to nerve injury, stiffness, and venous thromboembolism also cause significant morbidity. Hardware-related complications from graft fixation implants may occur either in the intra-operative or the post-operative period. It is important to be aware of these complications and their causative factors, so that risk mitigation and avoidance of such events can be undertaken. Awareness of the above, early recognition, and timely intervention are critical for a desirable outcome.