This paper summarizes the clinical and genetic features of a disease occurring in 16 patients from the same extended family, which resembles the multi-infarct dementia described by Sourander and Wålinder [Acta neuropath. 39: 247-254, 1977]. This family has relapsing strokes with neuropsychiatric symptoms, and they affect relatively young adult individuals of both sexes. The entity of the disease is characterized by autosomal dominant transmission with late onset and by association with occlusive cerebrovascular infarcts in the white matter, which was also generally reduced. Both of these features can be seen in the CT scan. In 13 members of this family the diagnosis can be regarded as certain and in a further 3 cases as more or less probable.