At least 20 different lacunar syndromes have been described and can be recognized by characteristic clinical features. Almost all occur in patients with hypertension. Small lacunes are usually due to lipohyalinosis, larger ones to atheromatous or embolic occlusion of a penetrating vessel. The concept of the "lacunar state" is examined in the light of recent knowledge with the conclusion that the clinical deficit is primarily related to unrecognized normal pressure hydrocephalus rather than to the presence of a few lacunes. The notion that lacunes occur haphazardly is criticized because the first or only lacune tends to be symptomatic. The incidence of cerebral lacunes has declined since the introduction of antihypertensive therapy, an indication that therapy is effective.