BACKGROUND Blue nevi are small acquired melanocytic tumors. Two clinical forms are described, a fibrous form and a cellular form. Giant nevi are exceptional. METHODS We describe a patient with a giant blue nevus of the scalp. In addition to this congenital, noninvasive tumor the patient presented numerous cutaneous melanocytic nevi. The main lesion was removed by surgical exeresis followed later with reconstruction plasty. The histological examination of the surgical specimen showed an infiltrating blue cell nevi. After a 4-year follow-up, there has been no recurrence and no metastasis. CONCLUSIONS There have been 11 cases of giant blue nevi reported in the literature. All were congenital lesions with polymorphous clinical and histological aspects. Fibrous forms are noninvasive and cellular forms have a potential for local invasion, whether shortly after birth or later with invasion of muscles, bone and meninges without intracerebral extension. Congenital blue nevi require early surgical exeresis.