Occasional patients with senile or presenile dementia respond favorably to steroid therapy. In addition to endocrinopathy and increased intracranial pressure, inflammatory processes and vasculitides can cause dementia and be sensitive to steroids. The author reports four such cases. A brain biopsy can be of great value for definitive diagnosis; it should be considered particularly in unusual, fulminant, and unexplained cases of dementia. A trial course of several weeks of steroid therapy can be given for such cases, but steroids should not be continued if improvement is not clearly apparent.