The purpose of this study was to compare two treatments for orthostatic hypotension, midodrine (an alpha adrenergic agonist), and octreotide (an SRIH analogue) to each other and to combination therapy. Sixteen patients participated. Our hypothesis was that the 2 drugs together would be more effective than either drug alone. The effect of the drugs on the hemodynamic response to food ingestion was evaluated while patients were sitting. Midodrine (5 mg orally, 30 min before breakfast) increased mean blood pressure slightly (5-10 mm Hg, over 30 min) before the patients started eating, but it only partially reversed the hypotensive effect of food ingestion. The nadir in postprandial blood pressure after midodrine was 69 +/- 4 mm Hg, not different from placebo (63 +/- 5). Nevertheless, midodrine accentuated the response to sc octreotide (0.5 microgram/kg). Fifteen minutes after octreotide administration to midodrine-pretreated patients, the average mean blood pressure was 115 +/- 9 mm Hg, higher (P = .0095) than after octreotide given alone (102 +/- 7). Drug effects on orthostatic hypotension were assessed by measuring standing time (minutes before symptoms of hypotension or definite hypotension). In the absence of treatment, standing time was 3.5 +/- 7 min; 1 h after 10 mg midodrine, 8.4 +/- 2.7 min (P = .11); after 1.0 microgram/kg octreotide, 13.2 +/- 3.9 min (P = .0034 vs. no treatment); and after both drugs, 21.2 +/- 5.5 min (P = .0002 vs. no treatment, P = .036 vs. octreotide only). The combination of midodrine and octreotide is more potent than either drug alone.