Abstract Objective Essential tremor (ET) is an involuntary postural oscillation. It is unclear to which extent motor cortical activity in preparation of volitional movement is abnormal in ET. We measured the Bereitschaftspotential (BP) to address this question. Methods Given the known influence of the cerebello-dentato-thalamo-cortical projection in the generation of the BP, patients were divided into two groups, defined by purely postural tremor (ETPT ) or additional presence of intention tremor (ETIT ) and compared to healthy controls. BP was recorded during self-paced rapid wrist extension movements. Results The late BP (500–0 ms before movement onset) was increased over the mid-frontal area in ETPT , whereas it was reduced over the mid-parietal area in ETIT when compared to healthy controls. In addition, the late BP was reduced over a widespread centro-parietal area in ETIT compared to ETPT. Conclusions Findings suggest that presence vs. absence of cerebellar signs (intention tremor) in ET results in differential affection of volitional preparatory motor cortical activity. The BP increase in ETPT may indicate compensatory activity, whereas the widespread centro-parietal BP reduction in ETIT suggests dysfunction of the cerebello-dentato-thalamo-cortical projection. Significance Reduction of the late BP amplitude may serve as a surrogate marker for dysfunction of the cerebello-dentato-thalamo-cortical projection in ET.