Neurofibromatosis type 1 is fully penetrant by the age of 8 years, and 3 criteria of diagnosis are dermatological: café-au-lait spots (CLS), intertriginous freckling and neurofibromas (NF). The aim of our study was to determine the evolving pattern of cutaneous manifestations during adulthood. Phenotypic data of patients seen in our center between March 2003 and December 2009 were studied. Patients were classified in 10-year groups. Following clinical characteristics, the number of CLS and the number of cutaneous and subcutaneous NF were compared according to age. 728 subjects, 404 females and 324 males (mean age of 32.4 years, range 6–80 years) were studied. Four hundred eighty-nine patients were over 20 years old (67%). The number of CLS (small or large) was significantly decreased with age while the number of cutaneous and subcutaneous NF was strongly increased (p< 0.001). The decrease in CLS with age has not been previously reported while an increase in the number of NF is well described during puberty and pregnancy and with age.