Cognitive impairment is a common phenomenon in children with neurofibromatosis type 1 (NF1), but only little is known about its nature and frequency in adult NF1-patients. Using a comprehensive psychometric test battery, we investigated 20 patients with NF1 and 20 age and gender matched control subjects without neurological diseases. Results showed slightly lowered test scores in patients compared with controls but no specific intellectual impairment. On a computerized test of selective attention, the NF1-group had significant slower reaction times. Also, three out of four memory tests and a test of visuoconstructive abilities showed poorer test results in the NF1-patients. Executive functions however were not affected. The findings agreed well with the test profile in NF1-children and supported the idea of a continuum between childhood and adulthood. Observations are discussed in the context of studies investigating the association of cognitive deficits with either intracranial lesions or alterations in the neurofibromin expression.