The long-acting somatostatin analogue SMS 201-995 was administered to a six-month-old infant with intractable diarrhea after failure of conventional treatment. During eight weeks of treatment, the secretory component of the diarrhea was positively influenced with a reduction of daily stool weight and stool sodium concentration. Plasma levels of growth hormone were markedly, and levels of insulin, IGF I, gastrin, pancreatic polypeptide, VIP, and neurotensin moderately decreased. Linear growth was also inhibited. The patient unexpectedly died from fulminant colitis at a time, when the dosage had been reduced from 18 to 3.5 micrograms/kg/day. The relationship, if any, between therapy with SMS 201-995 and the colitis remained unclear. It is concluded that SMS 201-995 can be effective in reducing secretory diarrhea in infants. However, further studies are necessary to assess the safety of its administration in this age group.