The objectives of this study were to estimate the frequency of cytomegalovirus (CMV) pneumonia and describe its clinical and radiological presentation in adult nontransplantation patients with cancer. Of the 10,441 autopsies performed at M. D. Anderson Cancer Center (Houston) during the period of January 1964 through December 1990, 9,029 were evaluable. Twenty histopathologically confirmed cases of CMV pneumonia were found, representing a frequency of 2.2 cases per 1,000 autopsies. When the frequency of CMV pneumonia was compared for the periods 1964-1979 (1.5 cases per 1,000 autopsies) and 1980-1990 (4.6 cases per 1,000 autopsies), a statistically significant increase due to an increase in the number of patients with solid malignancies was observed (P < .05). CMV pneumonia is an uncommon diagnosis at autopsy for adult nontransplantation patients with cancer and is usually found in conjunction with a disseminated neoplastic process.