Two cases of idiopathic orthostatic hypotension are reported, one associated with striato-nigral degeneration (case 1) and the other with Lewy body parkinsonism (case 2). In case 1, cerebrospinal fluid monoamine studies were carried out before and during treatment with 5-HTP and L-dopa. Low values of 5-HIAA appeared to be associated with degeneration of the spinal cord intermedi-olateral column. L-dopa had a beneficial effect on both parkinsonism and hypotension over a period of 6 months. New pathologic observations included changes in the sacral cord and a topographically related involvement of the substantia nigra and striatum, consistent with recent experimental neuroanatomical data.