Nocturnal sleep was poligraphycally recorded in three male patients aged 54-67, with progressive supranuclear palsy (PSP). All patients suffered from insomnia. In case 1 REM sleep was markedly reduced and spindles were less numerous than in normal subjects. In cases 2 and 3, EEG patterns were not distinguishable from those observed when the patients were awake. Sleep, therefore, was recognized only by constant observation of the patients. As seen in the literature EEG changes during sleep can be correlated to the severity of the clinical picture and the stage of evolution of the disease. EEG patterns of sleep in PSP are similar to those reported in patients with presenile dementia.