PURPOSE: Von Hippel-Lindau (VHL) is a rare hereditary and potentially fatal cancer syndrome. Because of its unpredictable manifestations in various organ systems, surveillance is not linked to a single department and may therefore be incomplete. Denmark published national guidelines for the surveillance of patients with manifest and possible VHL in 2005 and was one of the first countries to do so. The present study is the first of its kind; patients with suspected and manifest VHL were followed at a single institution according to the national guidelines. The purpose was to evaluate (1) to what extent the guidelines were being followed and (2) what findings were disclosed. METHODS: The study included 27 individuals with diagnosed (14 patients) or suspected (13 patients) VHL, observing the Danish VHL guidelines at the Department of Neurosurgery, Rigshospitalet, Denmark, from October 2002 to April 2008. The data were collected by reviewing patient records. RESULTS: Manifestations that influenced the treatment were revealed in 48% of the patients, and 26% of the patients demonstrated asymptomatic manifestations. All investigations were conducted at a lower frequency than recommended. Individuals diagnosed with VHL were subjected to more clinical testing than individuals with suspected VHL. CONCLUSIONS: This study shows that the national clinical guidelines were not being fully complied with. The investigations revealing the most serious VHL manifestations were those carried out with a frequency closest to the recommendations. Many investigations led to clinical consequences. Therefore, we recommend that all patients with suspected or manifest VHL are monitored according to structured clinical guidelines.