BACKGROUND : Severe abdominal pain caused by a rectus sheath hematoma (RSH) can decrease a patient's activities of daily living. A case of postoperative RSH for which a continuous rectus sheath block (RSB) was effective is reported. METHODS : A 62-year-old woman who had no previous medical history underwent hysterectomy, total cystectomy, and ileal conduit surgery for bladder cancer under epidural and general anesthesia. She complained of severe abdominal pain 40 min after removal of the epidural catheter on postoperative day (POD) 4. Computed tomography showed an RSH on POD 12. For pain relief, an ultrasound-guided continuous RSB was performed on POD 17. After the block, the numerical rating scale (NRS) score during movement decreased immediately (from 10 to 2 or 3), and she had no further need for oral or intravenous analgesics. She was discharged from the hospital without any complications on POD 28. CONCLUSIONS : Continuous RSB can be an effective technique for pain relief of postoperative RSH.