Low-molecular-weight heparins provide new options for outpatient management of deep venous thrombosis. Because elderly patients with cancer are at increased risk of developing deep venous thrombosis, outpatient therapy for treatment of deep venous thrombosis may be important in this population. We compared the severity of illness, outcomes, and cost of deep venous thrombosis in elderly patients with cancer to those seen in younger patients with cancer. We examined all 766 episodes of deep venous thrombosis treated at the University of Texas M.D. Anderson Cancer Center between January 1, 1994 and December 31, 1996. Severity of illness level and predicted risks of mortality and readmission were obtained from a commercially available disease staging system (Inforum System). Observed outcomes and cost were based on data collected from the 766 episodes of deep venous thrombosis at our institution. One hundred nineteen (16%) episodes of deep venous thrombosis occurred in patients 70 years of age or older. The severity of illness scale (1-5, least-most severe) were identical (3.7) in the 3 groups studied (< 70 years, 70-79, years and > or = 80 years). The predicted risk of death during hospitalization (6%, 9%, 8%, respectively, by group, P = 0.12) and readmission in 30 days (5%, 4%, 3%, respectively, P = 0.04) were similar among the groups. The observed death rates during hospitalization were 5%, 6%, and 6%, respectively (P = 0.91), and the rates of hospitalization for deep venous thrombosis recurrence were 22%, 16%, and 28%, respectively (P = 0.27). The similarities in outcomes and resource use between elderly and younger patients suggest that elderly patients with cancer are not at greater risk of serious clinical outcomes or a prolonged clinical course. There is significant potential for outpatient management of these patients.