The aim of this report is to point out the potential seriousness of the scombroid syndrome which, on the basis of our experience, can be characterized by extremely serious symptoms. We describe 12 cases of scombroid syndrome: two-thirds of the patients presented with rapid worsening of their clinical condition and hypotension severe enough to require use of plasma-expanders and hospitalization in an Internal Medicine Department. In the youngest patient, hypotension and symptoms were so marked that intravenous administration of epinephrine, and hospitalization in the Intensive Care Unit were required. Thus, in contrast to reports in the literature, the scombroid syndrome should be considered as a potentially serious ichthyotoxicosis. The pathogenetic role played by histamine, poorly absorbed by the intestine and rapidly metabolized by the liver, should be reevaluated. The potential onset of serious clinical symptoms warrants prolonged observation of the patient in an environment equipped to deal with the not infrequent emergencies that can arise, even in young and healthy subjects.