The purpose of this paper is to draw attention to one particular variant of tremor named "cortical tremor," which corresponds to rhythmic cortical myoclonus whose principal differential diagnosis is essential tremor. Diagnosis may be established with electrophysiological explorations (electromyography, accelerometry, electroencelography with back averaging, long latency reflexes, giant somesthesic evoked potentials). Clinical and electrophysiological features of 15 patients are reported and compared to cases previously published. Association with generalized or partial seizures is possible. Other cases in the family are often mentioned with a dominant autosomal transmission. The therapeutic approach is based on the use of antiepileptic drugs.