Prescribing patterns for parenteral morphine for symptom control in advanced cancer were studied in 50 consecutive hospital admissions (27 men, 23 women, median age, 62 years). Patients were interviewed daily (median time, 9 days) concerning analgesia while they were receiving parenteral morphine. Five major inpatient prescribing patterns were identified: (1) intravenous to oral, (2) intravenous to subcutaneous, (3) intravenous only, (4) subcutaneous only, and (5) mixed. The intravenoustooral group had more stable pain control than the intravenous-to-subcutaneous group. Pain control was good in the mixed group, suggesting that flexibility in the route of administration contributes to better pain control. Patients with neuropathic pain required higher doses of morphine. These patterns of parenteral morphine application reflect the complexity of the challenge presented by the various cancer pain syndromes. Physicians should be knowledgeable about the appropriate and flexible use of different routes of administration for morphine and other opioids.