The pharmacokinetics of oral and intravenous high dose methylprednisolone (Solu-medrone, Upjohn) were compared in patients with hematological malignancies. The aim of the study was to determine the oral bioavailability of high dose methylprednisolone and to establish whether this is a feasible and more convenient route of administration. The plasma pharmacokinetics were described by a one-compartment open model with peak plasma levels of 6.9 +/- 2.5 micrograms/ml. Total area under the plasma concentration versus time curve was similar by either route. Mean relative oral bioavailability was generally high (91 +/- 27 per cent). Retrospective analysis of 34 patients with chronic lymphocytic leukemia (CLL), non-Hodgkin's and Hodgkin's lymphoma treated with high dose methylprednisolone showed 11 responses including two complete remissions among nine patients with CLL. There was significant improvement in platelet counts in thrombocytopenic patients and treatment was well tolerated and toxicity was relatively low. High dose methylprednisolone may therefore be a useful palliative treatment for hematological malignancies, particularly where marrow suppression is a problem.