Cancer is the leading cause of death by disease in Taiwan. Most of the cancer patients have problems with pain, and they receive poor control of their pain. Cancer pain is an all-encompassing pain, which includes the physical, psychological and socio-economic aspects. The evaluation of cancer pain is very important, and there are many methods used for the evaluation. The World Health Organization has suggested the three ladder principle for managing cancer pain. Morphine is the most commonly suggested drug to treat cancer pain. Morphine was also the most important indicator of the pain control. Recently, the Fentanyl TTS Patch has been commonly used. It provides convenience and the least number of side effects. The cancer patients can maintain better life quality, but there are still many problems concerning the psychological and socio-economic pain. Therefore more professional workers need to be involved to resolve this problem.