This paper describes a simple method for comparing the effectiveness and costs of different cancer control activities and illustrates use of the method by evaluating priorities for controlling oral cancer in developing countries. The method estimates the long-term effect of prevention, screening, detection, treatment, and support activities (e.g., pain control) on morbidity, mortality, measures of quality of life, and cost for a specified population. It can be used to compare the cost effectiveness of various combinations of activities for one or more cancers and to help set priorities for cancer control programs. An analysis of two primary prevention activities, two screening activities, and three treatment activities to control oral cancer in Sri Lanka indicates that highest priority should be given to primary prevention activities such as anti-tobacco education and to screening.