Forty-six patients with refractory malignant lymphoma (Hodgkin's and non-Hodgkin's) admitted for autologous marrow or peripheral blood stem cell transplantation (ASCT) were evaluated for the presence of hemostatic abnormalities known to be associated with a hypercoagulable state in other patient populations. All patients had received numerous chemotherapeutic agents in the past and often radiation therapy as well. Hemostatic abnormalities were found to be common in these patients. The most frequent finding was hyperfibrinogenemia, present in 35% of patients. Decreased protein C activity was present in 32% of patients. Protein C antigen was low in only one individual and protein S was normal or increased in all patients. Low levels of antithrombin III were present in 16%. Plasminogen activator inhibitor was elevated in 20%. Anticardiolipin antibodies were present in 29% of patients; other evidence of a lupus anticoagulant was present in only eight patients. The frequency of each hemostatic abnormality was similar for patients with Hodgkin's disease (HD) and those with non-Hodgkin's lymphoma (NHL) despite the fact that significantly more patients with HD had received irradiation and/or previous splenectomy than patients with NHL. We conclude that multiple prothrombotic abnormalities of hemostasis are present in patients with refractory lymphoma referred for ASCT. Whether these are the result of lymphoma or the result of therapy cannot be determined from this study.