Six to 12 cycles of CMF is regarded as the standard regimen for adjuvant chemotherapy for breast cancer, producing 10-20% increase in survival for premenopausal and node-positive patients. Tamoxifen combined with CMF has induced an additional reduction in recurrence rate only in postmenopausal patients. Oral administration of 5-FU or its derivatives combined with tamoxifen for as long as 1-2 years is the regimen most widely used in Japan for considerable improvement in survival. But it needs further evaluation in comparison with CMF, and in ultimate duration of treatment and better combination with other drugs. Adjuvant chemotherapy for node-negative patients is advocated in the U.S., where the recurrence rate is as high as 30%. Only 10% of Japanese n0 patients undergo recurrence. Therefore, adjuvant therapy should be given only to high-risk patients.