« Penicillin allergy » is a common finding in patient's medical files (up to 10 %). Although it is important not to neglect such records (due to the serious and life-threatening reactions an allergic patient may suffer from), most of the time these reported notions of allergy are wrong and lead to the unfortunate avoidance of all betalactamins. This in turn leads to increased risks of antibiotic resistance and increased health costs. This review aims to summarize the current knowledge on penicillin allergy epidemiologic data and proposes a first-line guide for general practitioners to the evaluation of the patient with a history of « penicillin allergy ».