This issue of Pediatric Clinics covers Birthmarks of Medical Significance. Guest Editors Drs. Beth Drolet and Maria Garzon have assembled a panel of experts who offer reviews on topics including Vascular birthmarks: Introduction and classification, Infantile hemangioma, Other vascular tumors, Coagulopathy associated with vascular tumors/Kassabach-Merrit Phenomenon, Vascular malformations, Genetics and syndromes, Pigmentary mosaicism, Café au lait, Congenital melanocytic nevi, Dermal melanocytosis, and Epidermal nevi and nevus sebaceous.