OBJECTIVE The association of drugs with different mechanisms of action in the dorsal horn of the spinal cord decreases postoperative pain, with a reduction in the incidence of side effects. The aim of this study was to evaluate postoperative analgesia and sedation by epidural S(+) ketamine and S(+) ketamine-morphine associated with ropivacaine in subcostal cholecystectomy. METHODS Seventy patients of both genders, physical status ASA I and II, participated in this study. The following drugs were administered epidurally: 0.75% ropivacaine associated with 0.9% sodium chloride in the Control Group (CG); 0.75% ropivacaine associated with S(+) ketamine (0.5 mg kg(-1)) in the Ketamine Group (KG); 0.75% ropivacaine associated with S(+) ketamine (0.5 mg kg(-1)) and morphine (2 mg) in the Ketamine-Morphine Group2 (KMG2); 0.75% ropivacaine associated with S(+) ketamine (0.5 mg kg(-1)) and morphine (3 mg) in the Ketamine-Morphine Group3 (KMG3). Analgesia and sedation were evaluated 2h, 6h, and 24h after the end of the surgery. RESULTS Sedation was observed up to 2 hours after the end of the procedure in KG, KMG2, and KMG3. Analgesia was effective in CG up to 2 hours after the surgery, at 2h and 6h in KG, and at 2h, 6h, and 24h, in KMG2 and KMG3. CONCLUSIONS S(+) ketamine and the associations S(+) ketamine-morphine promoted sedation up to 2h after the end of the surgical procedure. S(+) ketamine promoted analgesia especially at the moment of the 2h observation, and the associations of S(+) ketamine-morphine promoted analgesia especially at 2h and 6h after the surgery.