Hen's egg allergy is the second major cause of food allergy in children and is rare in adults. It can present with diverse and sometimes severe symptoms that can be challenging for patients and clinicians. Allergy history represents the main diagnostic tool, and can be completed with skin tests, specific IgE testing and in selected cases with an oral challenge test. All patients with egg anaphylaxis should benefit from an emergency kit in case of reaction and specialized allergologic evaluation. Strict eviction of eggs can be difficult to achieve because of hidden allergens. For safety purpose, an oral tolerance induction is helpful selected patients. A pre-vaccination assessment is required in rare selected cases.