Intraluminal pressures of the gastric antrum, duodenum and jejunum were recorded for 206 min after a 12 h fast in a patient with carcinoid syndrome due to neoplasia of enterochromaffin cells of the ileum and with hepatic metastases. The most conspicuous alteration was a tachyrrhythmia of 16 waves/min predominating in the activity fronts of both duodenum and jejunum. Periods of 11-12 waves/min frequency appeared irregularly and the simultaneous occurrence of frequencies of 11 waves/min and 16 waves/min was also recorded. The gastric antrum was fully quiescent throughout the study. The alterations observed are presumed to be produced by substances secreted by the carcinoid tumor.