Six patients with short intestine (jejunal length 25-70 cm) on long-term parenteral nutrition, needing 4-5 L of intravenous fluid daily, were given octreotide (a somatostatin analogue, SMS 201-995) to investigate whether it would reduce beneficially their secretory diarrhoea (3.6-6.9 kg/day). They consumed the same diet for 2 control days, followed by 2 test days. Octreotide was given intravenously, initially in a dose of 50 micrograms b.d. through the central feeding line. There was a significant reduction of daily stomal output (0.5-5.0 kg) and daily sodium and potassium output; however there was no significant change in energy absorption. The response to octreotide was greatest in those patients who absorbed least nutrients. A dose increase to 100 micrograms t.d.s. gave no further measurable benefit though the patients found it smoothed-out the post-prandial rise in stomal output. Two patients were continued on long-term octreotide therapy, which allowed for a daily reduction in intravenous fluid of 1 and 1.5 L. Octreotide's anti-secretory effect was found to have been maintained when it was retested in one patient after a year of continuous therapy.