The patient with a history of current opioid consumption presenting in the acute postoperative setting presents a challenge for pain management. Standard treatment dosages and strategies are often ineffective in providing pain relief. This retrospective case-control study reviews 4 years' experience of the Acute Pain Service (APS) at our institution providing care for 202 chronic pain and opioid-consuming (CPOC) patients, 6.6% of 3058 patients undergoing urologic, gynecologic, orthopedic and general surgical procedures. Controls matched for age, gender, date and type of surgery, and postoperative pain relief modality were found for 180 (89%) of these patients. Patients were provided patient-controlled analgesia (PCA), or epidural opioid analgesia (EOA with boluses of preservative-free morphine or bupivacaine (1:16% + 2 micrograms/ml fentanyl (B/F)). Records were reviewed for patient demographics, diagnoses, surgical procedures, pre-operative opioid use, days-on-service, analgesic requirement, pain scores and incidence of moderate/severe side effects. Patient demographics were similar between CPOC and control groups. When considering PCA alone, mean 24-h usage in controls was 42.8 (32.0) mg morphine (MS) equivalents differing significantly from CPOC patients' use of 135.8 (68.5) mg MS equivalents (P = 0.0001). EOA and B/F case studies showed similar results. Moderate sedation was experienced by 50% of CPOC patients receiving PCA. Differences in opioid usage, side effects, pain scores, sedation and prescribed treatment with anxiolytics were shown between CPOC patients and matched controls.(ABSTRACT TRUNCATED AT 250 WORDS)