The Japanese Quality of Life Research Group has developed a general questionnaire suitable for assessing the Quality of Life (QOL) in patients undergoing chemotherapy. The questionnaire covers four major categories: (1) daily activities, (2) physical condition, (3) social activities, and (4) mental and psychological status. The State-Trait Anxiety Inventory (STAI), Self-Rating Depression Scale (SDS), and Performance Status (PS) were used as external measures of quality of life and for the validation of our tool. On the basis of two basic surveys and two studies we selected 22 questions from a larger set of items. Validity and reliability were verified for the final 22-question form. This questionnaire, named the QOL Questionnaire for Cancer Patients Treated with Anticancer Drugs (QOL-ACD), can be used to detect changes in QOL over time. Its use as an additional outcome measure in Phase III chemotherapy trials should be encouraged.