Vascular disease is an underestimated complication of neurofibromatosis type 1 (NF1). The few studies available on this disease are based on case reports. The purpose of this study was to evaluate the relationship between 24-h systolic blood pressure (SBP) and 24-h heart rate obtained by ambulatory blood pressure monitoring and the carotid femoral pulse wave velocity, a widely used index of arterial distensibility, evaluated with Complior. We studied 64 young NF1 patients and 30 healthy subjects. There was no difference in pulse wave velocity between NF1 patients and healthy subjects. Ten of the NF1 patients showed 24-h SBP or 24-h diastolic blood pressure (DBP) >95th percentile for age and sex. We divided the NF1 group into subgroups: NF1 patients with 24-h SBP and 24-h DBP < or = 95th percentile for age and sex (NF1A group) and NF1 patients with mean SBP or DBP >95th percentile for age and sex (NF1B group). The pulse wave velocity of NF1A and NF1B patients were 6.3 +/- 1 m/sec and 6.4 +/- 1 m/sec, respectively (P = not significant). A significant relationship was found between 24-h SBP, 24-h heart rate, and pulse wave velocity in healthy subjects, but not in all NF1 patients and also between the NF1A and NF1B groups. Distensibility of the central arteries may be altered by various environmental or genetic factors. Thus, genetic determinants may play a role in the response of the large arteries to blood pressure. The recent discovery of neurofibromin in aortic smooth muscle may explain the vascular abnormalities present in NF1 patients. We emphasize the importance of a careful vascular evaluation using a noninvasive method, such as Complior and a periodic ambulatory blood pressure monitoring to detect NF1 patients at high risk of vascular complications.