131I MIBG scintigraphy is of great value in the diagnosis and the treatment of several tumors derived from the neural crest. But, its role in the assessment of carcinoid tumors remains to be evaluated. It was the aim of this prospective study. Between 1987 and 1989, 14 consecutive patients with carcinoid tumors were studied. Planar scintigrams were obtained 24 and 48 hours after the intravenous injection of 74 MBq of 131I MIBG. At least one scintigraphy was performed in every patient; at that time one or several abdominal tumor sites (a total of 22 sites) were found and histologically proven. Scintigram was judged as positive in 9 of 14 patients (64 p. 100); 68 percent of the 22 tumor sites and 86 percent of the 14 extra-hepatic tumor sites took up 131I MIBG. Liver metastases were overlooked on scintigrams in 5 of 8 patients. Scintigraphy was the only positive examination in 3 patients. No false positive scintigrams were noticed. These results emphasize the value of 131I MIBG scintigraphy in the assessment of carcinoid value tumors.