In a prospective study, 47 out of 55 patients with benign paroxysmal positional nystagmus (BPN) were reexamined after 3-41/2 years. In a third of these patients head injury was found to be the cause of positional nystagmus. In a few patients BPN was found to be directly connected with non-traumatic labyrinth affection, intermittent vertebro-basilar insufficiency, or anaesthesia. In a quarter of the patients no causative factors were found. In 44% of the patients nystagmus disappeared in an average of 8.6 months. In the follow-up a quarter of the patients (28%) still suffered regularly from positional nystagmus. Finally, in another quarter of the patients (28%), episodic nystagmus occurred over years and averaged 3.6 episodes per patient. The course of BPN is therefore more resistant and less predictable than was previously believed. However, most patients learn to adjust to the symptom and are only mildly handicapped by BPN.