The definition of the roles of surgery and radiation therapy in controlling local malignant disease has become much clearer in the past two decades. Nonetheless, most patients who die of their malignancy do so from metastatic disease. With the advent of effective combination chemotherapy for many patients with advanced malignant disease, the employment of systemic treatment at an earlier stage has become a clinical possibility. Important advances in the systemic control of a number of malignancies have been described. These are examples of a few of the presently ongoing trials (Salmon and Jones, 1977). For the merits and demerits of prophylactic systemic treatments to be accurately determined in malignant disease, it is important that the future role of adjuvant chemotherapy in man be evaluated only in the context of carefully controlled clinical trials. The fact that adjuvant therapy is effective in prolonging survival in some malignant diseases is established; its role in many of the commoner malignant diseases awaits more complete evaluation.