An open pilot study was undertaken to evaluate the analgesic properties of epidurally administered sufentanil in the early postoperative period. After orthopaedic surgery of the lower extremity, four different groups of five adult patients each received either 15 micrograms (group 1), 30 micrograms (group 2), 50 micrograms (group 3) or 75 micrograms (group 4) sufentanil via an epidural catheter previously used for the surgical procedure. Results were satisfactory in groups 3 and 4 with very good relief of pain and a mean duration of action of 372 and 307 minutes respectively. Dosage above 50 micrograms did not seem to improve the quality or duration of pain relief, although the onset of action was faster with 75 micrograms. Sedation was always present in patients with effective analgesia. In the present study respiratory depression was not evident, but three patients complained of itching and two of urinary retention.