Methods are disclosed of treating or preventing hypotension (e.g., neurogenic orthostatic hypotension or postprandial hypotension) or portal hypertension (e.g., bleeding esophageal varices associated with portal hypertension) or ascites (e.g., ascites associated with liver cirrhosis), by oral administration to affected subjects of compositions comprising a therapeutically effective amount of terlipressin or a pharmaceutically acceptable salt thereof.