We report on three families in which cluster headache is present in more than one member. In one of these families a boy, his father, and paternal grandfather were affected. In the other two families, a father and son and mother and daughter were the affected members. Diagnoses were based on IHS criteria, after examining and taking the history directly from the patient in all but one of the seven cases; the seventh patient was deceased and the diagnosis was based on reports from the affected son. Considered in the light of other recent reports of familial cluster headache, these cases suggest that cluster headache can have a genetic component.