In a period of a little over 20 years, chemotherapy of cancer has evolved from a period of empiricism with little impact on the cancer problem to become part of a sound medical discipline with firm scientific underpinning playing an increasingly important role in the control of cancer. This progress has come from an increasing knowledge of cancer biology and pharmacology and the application of this knowledge to improved design of clinical trials, with due consideration to the intricacies of the natural history of each disease in question. Now that the chemotherapeutic tools are sharpened, their use in combinations with other modalities in the previously unfamiliar setting of the patient with early stages of the disease promises to lead to an even more exciting chapter in clinical cancer research in the next decade.