Kounis syndrome has been defined as an acute coronary syndrome that manifests as unstable vasospastic or nonvasospastic angina, and even as acute myocardial infarction. It is triggered by the release of inflammatory mediators following an allergic insult. We report 5 patients attended at our hospital between January 2005 and May 2008 who were diagnosed with unstable angina or acute myocardial infarction-according to analytical parameters, electrocardiographic abnormalities, and/or coronary angiography--in the context of an anaphylactic episode. Age at the time of the episode, age ranged between 50 and 68 years. The results of an allergology study revealed the causal agents to be drugs in 4 cases (nonsteroidal anti-inflammatory drugs and omeprazole) and food in 1 case (kiwi). Coronary disease of a blood vessel was observed in 2 patients. Serious allergic reactions may be the cause of acute coronary syndrome in patients with healthy or altered coronary arteries and no cardiovascular risk factors.