BACKGROUND: Masses of the lateral skull are not uncommon and include lipomas and epidermoids. However, meningoceles of the lateral skull are very rare and are often misdiagnosed. Even rarer are atretic encephaloceles of this region. ILLUSTRATIVE CASE: We report a newborn with a right atretic encephalocele of the asterion. Lesions of the anterolateral and posterolateral fontanelles should include lateral cephaloceles/encephaloceles in the differential diagnosis. The literature and embryology of these rare entities are discussed.