The effect on gut motility of a single subcutaneous injection of 50 micrograms of the long-acting somatostatin analogue, SMS 201-995, was investigated in 8 normal volunteers who took a drink containing 99mTc and lactulose with a mixed meal. The rate of gastric emptying was assessed by disappearance of the isotope from the stomach area as measured by a gamma camera, and mouth-to-caecum transit time (MCTT) was measured by the appearance of hydrogen in the breath. Gastric emptying was accelerated, with a significant reduction of the time taken to 50% isotope disappearance (37.2 +/- 3.3 min during control study vs 23.3 +/- 3.4 min after SMS injection; p less than 0.01). In contrast, MCTT was prolonged from 57.3 +/- 9.4 min (control) to 203.6 +/- 14.7 min after SMS (p less than 0.001).