Progressive supranuclear palsy (PSP) is one of the most frequent causes of an atypical parkinsonism. The cognitive disturbances in PSP gave rise to the term "subcortical dementia". Cognitive impairment is independent of depression, which is also common in PSP. There is no correlation between cognitive impairment and either disease duration or a level of physical disability. We present a clinical picture and difficulties in PSP diagnosis in three patients--63 to 74 years old, who were hospitalized in the Department of Neurology, Medical Academy in Bialystok. A neuropsychological evaluation revealed significant differences among those patients. The patients presented with: 1. depressive and dementive syndrome, 2. executive dysfunction, 3. slowed information processing with no signs of dementia. Our findings are similar with data presented in literature and confirm the observations that: 1. there is a difference in a degree of cognitive impairment in between the patients with PSP, 2. the most frequent cognitive disturbances in PSP patients are: slowness of thought process and executive dysfunction.