Six cases of neurological complications of essential thrombocythemia are reported. Five were ischemic strokes and the clinical expression was heterogenous (transient ischemic attacks or completed strokes), in vertebro-basilar or carotid areas. There was no correlation between the nervous disorders and the severity of the thrombocythemia. In the last case, the patient presented with papillitis and peripheral neuropathy, and the relationship with thrombocythemia was not clear. It is suggested that thrombocythemia may directly induce an arterial or venous thrombosis or increase the severity of ischemic strokes of atheromatous origin.