Pain affects many cancer patients, and in advanced stages of the disease it can significantly affect the quality of their lives. Morphine has long been the 'gold standard' for the treatment of cancer pain. However, its side-effects, particularly sedation and cognitive impairment at high doses, have encouraged the use of 'opioid rotation'. The transdermal fentanyl patch has advantages over oral morphine, with reduced side-effects and increased convenience in practical usage. The side-effects were reduced in patients who changed to the fentanyl patch, but rescue analgesia was often needed because of the decrease of fentanyl release from the patch, especially on the patch replacement day. We have developed a three-cycle fentanyl patch system that provided an appropriate pain control, and this system should be considered for pain relief in cancer patients.