Cancer patients frequently suffer from a myriad of symptoms. The development and application of comprehensive assessment tools is essential to the effective management of these symptoms. The M.D. Anderson Symptom Inventory (MDASI), developed in English, is a brief, self-rating multiple symptom assessment scale that consists of 13 symptom items and 6 interference items. We examined the validity and reliability of the Japanese version of this scale (MDASI-J) by evaluating 252 randomly selected cancer patients. They were asked to self-administer the MDASI-J and the European Organization for Research and Treatment of Cancer QLQ-C 30. Construct, criterion, convergent and discriminant validity, and reliability of the MDASI-J were evaluated and compared with corresponding data obtained in the previous study conducted in the United States. The results indicated that the MDASI-J is a valid and practical measure for assessing multiple symptoms in Japanese cancer patients. Both factor analysis and cluster analysis showed the consistency of the statistical structure of the English and Japanese versions, indicating the cross-cultural validity of the scale.