We report a patient with adolescent-onset, Rasmussen's encephalitis, presenting with intractable focal seizures, mild hemiparesis, cognitive impairment, dystonia, and severe hemiballism. His father had Behcet's disease, considered to be an autoimmune disorder. Recent reports have directly implicated the role of cytotoxic T lymphocytes in the pathogenesis of both Rasmussen's encephalitis and Behcet's disease. The Occurrence of Behcet's disease and Rasmussen's encephalitis in the same family suggests involvement of common genetic factors Such as HLA haplotypes in both autoimmune disorders. It is possible that members of this family are genetically susceptible to developing autoimmune conditions that have been precipitated by separate environmental triggers.