We estimated the number of cancer patients treated at hospitals with 200 or more general beds per day in Japan. Some 1,635 hospitals were asked to report the number of cancer patients who received any medical treatment on the survey day, which was generally November 21, 2002. The estimated total number of cancer outpatients was 114,767, which accounted for 63% of the estimated total cancer outpatients per day in Japan. The estimated number of cancer patients receiving chemotherapy was 25,289 per day; among them, 18,887 and 5,440 patients received anticancer drugs orally and intravenously, respectively. The estimated number of cancer patients receiving radiotherapy was 6,088 per day. At the time of this survey, 16% of the hospitals had outpatient chemotherapy units, 21% were planning to have such units, and 63% had no such plan. Because of limited medical resources, more patients will receive chemotherapy or radiotherapy on an outpatient basis. Further study should assess whether the state-of-the-art treatments are appropriately provided in the current outpatient chemotherapy or radiotherapy practice.