Progressive supranuclear palsy (PSP) is a sporadic tauopathy with insidious onset and a progressive course, first described in 1964 as parkinsonism, postural instability, axial rigidity, supranuclear gaze palsy, pseudobulbar palsy and cognitive changes. However a much broader clinical spectrum is now recognised in association with PSP. PSP may present as corticobasal syndrome (CBS) with asymmetric rigidity, apraxia, dystonia and variable cortical and basal ganglionic features.[3, 4] CBS was first reported in association with the pathological entity of corticobasal degeneration (CBD), but is now recognised to develop secondary to PSP pathology as well as Alzheimer’s disease, frontotemporal dementia, and other less common causes. This overlap contributes to difficulties with accurate ante-mortem diagnosis of both PSP and CBD. It has been suggested that myoclonus favours the likely pathological diagnosis of CBD rather than PSP,[7, 8] although very few pathologically proven cases of PSP have documented myoclonus.[9, 10] We report the clinical and neurophysiological features of cortical myoclonus in a patient with pathologically proven PSP, in order to highlight the clinical features that are helpful in distinguishing CBS arising from PSP compared with CBD pathology.