We have reviewed 90 patients from the literature with histopathological features compatible with currently accepted criteria for the diagnosis of the Steele-Richardson-Olszewski syndrome (SROS). Only 62 patients (69%) had clinically definite SROS based on the criteria of Maher and Lees. Neurofibrillary degeneration of subcortical structures with involvement of the internal pallidum, the subthalamic nucleus, and substantia nigra was considered essential for the pathological diagnosis. Thirty-six cases (40%) had neocortical neurofibrillary change that bore no clear relationship to the degree of cognitive impairment (chi 2 = 9.293; p < 0.4107). Grumose degeneration of the dentate nucleus was present in 25 cases (28%), and occasionally there were other, less usual, findings such as Pick bodies and Lewy bodies.