Transdermal (TTS) fentanyl therapy has emerged as an effective alternative to the use of oral opioids for the control of pain in certain cancer patients. These patients are those with moderate to severe chronic pain, with a stable baseline pain pattern. Patients receiving this treatment should first be titrated to stable pain relief with oral opioids and should have recourse during therapy to fast-acting, short-duration analgesics for the control of incident pain. TTS fentanyl dosing schedules should be based upon the patient's requirement for rescue dosing and duration of effective pain control. The average requirement to change fentanyl patches is every 72 h, although 48-h dosing is necessary in a few patients. This novel route of fentanyl administration allows convenient outpatient treatment, the possibility of a lower incidence of side effects, and may thus aid compliance.