cancer pain and evaluation of the pain preface and comments cancer pain is very unpleasant often difficult to treat therefore we should recognize the mechanisms of cancer pain and know the physical pain psychological pain social pain and spiritual pain as total pain besides we must understand how to evaluate the cancer pain using the methods of assessment of cancer pain and scales of pain degree vas nrs vrs frs fvas new devices of pain measurement and the character of painmcgill and yatabe are also introduced the mechanism and grade of cancer pain often confuse us to recognize cancer pain the articles in this special issue are useful for the evaluation and treatment of cancer pain i feel happy if these articles contribute to the treatment of patients with cancer pain