A chart review study was done of 242 Stages A2 to D1 cancer patients to determine whether the age of patients with prostate cancer influenced their physicians' management strategies. Ten hospitals of varying size, medical-school affiliation, and patient socioeconomic status participated in this study. Patterns of prostate cancer care were examined using sets of branching logic standards in the form of criteria maps. A chart-based comorbidity index was used to control for the effect of coexisting diseases on cancer management. Regression models indicated that patient age affected the intensity of both the diagnostic evaluation and therapy, even after controlling for independent factors such as comorbid disease and individual hospital differences. Patients aged 75 years and older had significantly less intensive clinical staging workups and use of surgical and radiation therapies compared with patients aged 65 to 74 years and patients aged 50 to 64 years. In conjunction with similar results noted in studies of elderly patients with other malignancies, these results suggest that age bias is likely to be widespread. Physicians need to consider life expectancy, the ability of the patient to tolerate diagnostic procedures and therapies, and the quality of life in making treatment decisions.