591 patients scheduled to undergo major orthopedic surgery were randomized to receive either sublingual sufentanil or intravenous patient-controlled morphine for postoperative analgesia. This was done to assess the onset of action of a sufentanil sublingual tablet system compared to that of intravenous patient-controlled analgesic morphine. Pain intensity and patient and nurse ease-of-care ratings were assessed. Results indicated that patients who had received sufentanil after knee arthroplasty experienced a significantly greater pain intensity difference from 45 minutes to 6 hours following drug administration, when compared to patients who had received morphine. Patients who had received sufentanil after hip arthroplasty experienced a significantly greater pain intensity difference from 1 to 4 hours following drug administration. Sufentanil treatment also demonstrated better ease-of-care parameters from both nurses and patients.