AbstractTwo patients who had severe carcinoid syndrome are presented. In one patient prednisone relieved symptoms for 20 months, and in the second patient chemotherapy appears to have precipitated fatal carcinoid crisis. Changes in mentation, increased frequency and intensity of flushing, and hypotension indicate increased risk of a chemotherapy induced carcinoid crisis. Since prednisone may produce relatively long control of carcinoid syndrome, it should be tried before chemotherapy in patients who have increased risk of carcinoid crisis. If chemotherapy is given, doses should be decreased by 50%, and patients should be followed closely.