We prospectively analyzed 286 consecutive patients with lacunar syndromes. Using neuroimaging, 227 patients (80%) had findings compatible with occlusion of a single penetrating artery (presumed lacunar infarct), whereas other lesions were found in 59 patients (20%). The mean age of patients with lacunar syndromes not due to lacunar infarcts (nonlacunar patients) was 56 ± 14 years; 37 patients (63%) were males. The causes were: cerebral hemorrhage (30), large cerebral infarct (26), demyelinating disease (1), cerebral metastasis (1) and cerebral angioma (1). Between nonlacunar and lacunar patients, there were significant differences in the mean age (56 vs. 60 years, p = 0,02), mean diastolic arterial tension on admission (90 vs. 94 mm Hg, p = 0.03); occurrence of diabetes mellitus (13 vs. 28%, p = 0.03), hemoglobin value (15 vs. 16 g/100 ml, p = 0.05), occurrence of headache (22 vs. 12%, p = 0.05), nausea or vomiting (17 vs. 8 %, p = 0.04), sensorimotor deficit (36 vs. 15 %, p = 000.6) and medical complications in the acute stage (54 vs. 18%, p = 0.0001). In conclusion, 1 of 5 patients with a lacunar syndrome may not have a lacunar infarct. Similar symptoms can also be caused by small hemorrhages and large infarcts, mainly in the subcortical striatocapsular region. In patients with a lacunar syndrome, neuroimaging is essential to exclude lesions other than lacunar infarctions.