Nineteen studies of advanced cancer in 8 disease sites have been examined using data from the Eastern Cooperative Oncology Group. The purpose of the investigation was to determine susceptibility of elderly patients (270 years of age) to cancer chemotherapy and to compare the results with corresponding figures in control patients (<70 years of age). The results indicate that in general, the elderly patients have identical rates of severe toxicity as their younger counterparts. The only exception is for hematologic reactions in a few of the sites studied. On closer examination, the agents that appear to be responsible for these especially adverse effects are methotrexate and methyl-CCNU. It is demonstrated that the elderly patients have similar response rates and survival expectancy to the nonelderly patients. Conse quently, it is concluded that the apparent discrimination in not treating elderly patients as aggressively as younger patients, and in excluding elderly patients from protocols, does not appear to be justified. Exclusions should be based on physiologic functional parameters, such as measures of renal, liver and marrow function, or performance status, rather than on an arbitrary age limit. Exceptions should only be made for agents which have a clearly demonstrated adverse effect on the elderly.