Background: Seizures are common in juvenile Huntington's disease (HD), but considered to be rare in adult-onset HD. We studied the occurrence of epilepsy and seizures in a nationwide cohort of Finnish patients with adult-onset HD. Methods: Patients with HD and their diagnoses of epilepsy or seizures were identified by a search into a nationwide registry. Cases were verified in a subsequent review of patient charts. Results: Three out of 114 HD patients alive on prevalence date had been diagnosed with epilepsy giving a prevalence of 2.6 % (95 % CI, 0.6-7.5). In addition, one patient with a single unprovoked seizure, one patient with a medication-induced seizure and two patients with transient nonspecific attacks were identified. Epilepsy was not associated with clinical severity of HD and seizures were controlled with antiepileptic medications (AEDs). Generalized tonic-clonic seizures (GTCs) were the most common seizure type. Conclusions: Prevalence of epilepsy is similar in patients with adult-onset HD compared to general population. Seizures are easily controlled with AEDs.