Nevi represent congenital hamartomatous malformations of various components of the skin. The most common forms are congenital melanocytic nevi (CMN) and nevi of epithelial origin (epidermal and organoid nevi). Large CMN in particular can lead to severe complications and the management of those affected represents a challenge from birth. In contrast to previous assumptions, the risk of malignancy from CMN is considered to be relatively low however, this may be relevantly increased in certain situations. Possible extracutaneous symptoms in cases of central nervous system (CNS) involvement should not be underestimated and early imaging investigations are part of the routine diagnostic procedure. Surgical measures are still very important in the treatment of CMN but the indications must be weighed up for each individual case. Patients often experience marked stigmatization due to disfigurement by their birthmark and this needs to be taken into consideration for their treatment. The most common epithelial nevi are sebaceous nevi. In 2-13 % of cases additional tumors occur within this nevus and early surgical excision is indicated in most cases, not least for aesthetic reasons. If generalized spreading of epidermal nevi occurs, additional investigations are necessary to exclude associated ophthalmological, cardiac or neurological malformations.