We describe an analysis of 227 patients with lacunar infarcts; 177 were inpatients and the remaining 50 were outpatients. The group comprised 11% of all inpatients with cerebrovascular pathology and 16% of all consecutive inpatients with brain infarcts studied at the Department of Neurology of the Hospital de la Santa Creu i Sant Pau. The main risk factors identified in these patients were arterial hypertension in 164 (72%), diabetes mellitus in 64 (28%), and heart disease in 58 (26%). The most common clinical syndromes were pure motor hemiparesis in 125 (55%), pure hemisensory stroke in 42 (18%), the sensorimotor deficit syndrome in 34 (15%), ataxic hemiparesis in seven (3%), and the dysarthria-clumsy hand syndrome in four (2%); atypical syndromes were observed in 15 patients (7%). Lacunes were demonstrated by computed tomography in 100 patients (44%) and by magnetic resonance imaging in 35 (78%) of the 45 patients in which it was applied. Magnetic resonance imaging was significantly better (p less than 0.001) than computed tomography for imaging lacunes, especially those located in either the pons (p less than 0.005) or the internal capsule (p less than 0.001). After the acute phase, mild or no neurologic disability was detected in 178 patients (78.4%), moderate disability persisted in 48 patients (21.1%), and severe disability was recorded in one case (0.4%). Lacunar infarcts are a clearly defined entity with characteristic clinical features and an excellent short-term prognosis. Magnetic resonance imaging is the current method of choice for demonstrating these small brain lesions.