To study the relationship between gastrointestinal dysfunction and motilin in patients with hypothyroidism. The plasma motilin concentration was measured by radiommunoassay(RIA) in 30 patients with hypothyroidism and also in 30 controls. At the same time, the electrogastroenterogram was also taken. Among the hypothyroidism patients, 56.6% had decreased gastric motility, especially in gastric body and greater gastric curvature; 86.6% had decreased colonic motility, especially in the left half of the colon. There were no significant differences of plasma motilin concentration between patients with hypothyroidism and controls (%P%>0.05). There were also no differences between pre-treatment and post-treatment individuals, but significant differences were observed in the electrogastroenterogram. We conclude that the plasma motilin concertration in hypothyroidism patients was the same as that in normal patients, and that electrogastroenterogram studies in patients with gastrointestinal dysfunction may be valuable. To study the relationship between gastrointestinal dysfunction and motilin in patients with hypothyroidism. The plasma motilin concentration was measured by radiommunoassay (RIA) in 30 patients with hypothyroidism and also in 30 controls. At the same time, the electrogastroenterogram was also taken. Among the hypothyroidism patients, 56.6% had decreased gastric motility, especially in gastric body and greater gastric curvature; 86.6% had decreased decreased colonic motility, especially in the left half of the colon. There were no significant differences of plasma motilin concentration between patients with hypothyroidism and controls We were also no differences between pre-treatment and post-treatment individuals, but significant differences were observed in the electrogastroenterogram. We conclude that the plasma motilin concertration in hypothyroidism patients was the same as that in normal patients, and that electrogastroenterogram studies in patients with gastrointe stinal dysfunction may be valuable.