Mastocytosis is a heterogeneous group of diseases characterized by the abnormal infiltration of mast cells in the skin and other organs. The most common type of cutaneous mastocytosis in children is urticaria pigmentosa. The term "bullous mastocytosis" is used to describe cases with mastocytosis in which bullae was a prominent feature. Systemic involvement is more frequent in this type. If typical lesions and symptoms are absent, the diagnosis of bullous mastocytosis is not always evident and other bullous diseases such as bullous impetigo, primary herpes simplex virus infection, immuno-bullous disease, neonatal lupus, incontinentia pigmenti and erythema multiforme could be considered. The mastocytosis is usually diagnosed with clinical and histopathological examination. In addition, the disease was recognized rapidly and promptly by a simple technique such as Tzanck smear. Here, we report a 20-day-old boy with neonatal bullous urticaria pigmentosa that was diagnosed rapidly with Tzanck smear.