OBJECTIVE: Reconstructive surgery of the ACL is one of the most commonly performed surgeries today and the control of postoperative pain is part of the priorities of the surgeon. Within the arsenal of analgesia we have the intra-articular application of drugs, and the most studied one is bupivacaine with or without morphine. This study compared the application of bupivacaine with or without morphine with a control group after ACL reconstruction with flexor tendon graft. METHODS: Forty-five patients were randomized into three groups: in group I, 20 ml of saline were applied intra-articularly at the end of the surgery; in group II, 20 ml of bupivacaine 0.25%; and in group III, bupivacaine 0.25% associated with 1 mg of morphine. The groups were assessed for degree of pain by the Visual Analog Scale at 6, 24 and 48 hours postoperatively. RESULTS: Group III had less pain at all times, but the pain was not as intense in all groups to the point of needing extra medications beyond the established protocol. CONCLUSION: The intra-articular application of these medications after ACL reconstruction with flexor tendon graft when performed under spinal anesthesia is not useful enough to use regularly. Level of Evidence II, Lesser quality RCT.