Neurofibromatosis type 1 (NF1) is the most common neurocutaneous syndrome and probably the one best known to dermatologists, who are generally the first physicians to suspect its diagnosis. Although the genetic locus of NF1 was identified on chromosome 17 in 1987, diagnosis of the disease is still mainly based on clinical observations and the diagnostic criteria of the National Institute of Health, dating from 1988. Cutaneous manifestations are particularly important because café-au-lait spots, freckling on flexural areas, and cutaneous neurofibromas comprise 3 of the 7 clinical diagnostic criteria. However, café-au-lait spots and freckling can also be present in other diseases. These manifestations are therefore not pathognomonic and are insufficient for definitive diagnosis in the early years of life. NF1 is a multisystemic disease associated with a predisposition to cancer. A multidisciplinary follow-up is necessary and dermatologists play an important role.