A case report of histamine (Scombrotoxin) poisoning is presented. Five to ninety minutes after eating cooked swordfish, 30 persons reported feverishness, diarrhea, palpitations, headache, nausea, dyspnea, generalized urticaria, angioedema, and shock. Of these, 13 persons were admitted to Saint Luke's International Hospital. The patients were given intravenous hydration, IV Hl-blocker, and subcutaneous epinephrine as needed. However, 4 patients required continuous administration of epinephrine intravenously for resolution of the anaphylactic shock. These patients required observation in our intensive care unit. On the following day, all the patients were well and ready for discharge from the hospital. There were no symptoms at the time of discharge. Quantitative determination of the plasma concentration of histamine at the time of admission revealed a value of 0.85-43.10ng/ml. Some pieces of the offending tuna were sent for analysis, and 670mg histamine per 100g of the fresh tuna and 750mg histamine per 100g of the cooked tuna were detected. Generally speaking, histamine poisoning is associated with only mild allergic symptoms. However, in this case, some people developed shock and required close observation. This experience suggests that histamine poisoning can be associated with an outbreak of anaphylactic shock and serves as a cautionary example for emergency medical staff.