Reports of tremor in progressive supranuclear palsy (PSP) have been infrequent; some authors indicate that tremor is never seen in PSP. Five patients with PSP and tremor are presented. Our series of cases and those reviewed in the literature suggest that tremor occurs in 12-16% of PSP cases. The rest tremor observed in 3 of our cases differed from the "pill-rolling" and "parkinsonian tremor" described in previously reported cases by being slower in rate (3 per second or less). This slow rest tremor is rarely seen in Parkinson's disease (4-6 per second). Our experience suggests that, contrary to previous opinions, tremor may be the presenting complaint and a prominent finding in PSP and the presence or absence of tremor is of no value in the differential diagnosis of PSP from Parkinson's disease.