Aim - In this study, we aimed to examine the risk factors, topographic features and stroke mechanisms of acute ischemic unilateral infarcts of thalamus. Methods - Patient with isolated thalamic infarct and those with posterior cerebral artery (PCA) infarction who were admitted to our hospital between January 2014 and January 2017 with acute unilateral thalamic infarction (TI) were included in this study (isolated thalamic infarction/ isolated TI; thalamic and posterior cerebral artery infarction/PCA+TI). Demographic characteristics and vascular risk factors of the patients were determined. Thalamic infarct areas were recorded topographically as anterior, posteromedial, ventrolateral, posterolateral, more than one area, and variant areas. Stroke mechanism was determined according to the criteria of „Trial of Org 10172 in Acute Stroke Treatment” (TOAST). Patients with isolated TI and PCA TI were compared according to risk factors, stroke mechanism and infarct topography. Results - Forty-three patients with a mean age of 63.3 ± 14.5 years were included in the study. Twenty-eight patients (60.1%) were found to have isolated TI and the remaining 15 patients (34.9%) had PCA+TI. 32.1% of patients with isolated TI had sensory symptoms on presentation, and 60% of patients with PCA-TI had sensorimotor symptoms. The mean age, the mean score on National Institutes of Health Stroke Scale (NIHSS) and the mean frequency of atrial fibrillation were higher in PCA+TI patients than in isolated-TI patients (p: 0.04, p: 0.004, p: 0.02 respectively). 32.6% of the patients had ventrolateral, 30.2% had posteromedial involvement. Ventrolateral topography was seen in 46.7% of the PCA+TI patients, while posteromedial topography was seen in 39.3% of the isolated-TI patients. 53.6% of the isolated-TI had small vessel disease etiology, while 40% of the PCA+TI had cardioembolic etiology, and the other 40% had large artery atherosclerosis. Conclusion - Our study showed that the most ommon stroke mechanism in patients with thalamic infarction is the small vessel disease. Isolated TI and PCA+TI patients differ in terms of etiologic mechanism and infarct topography. Variant territorial involvement and multiple area involvements can be quite common in thalamic infarcts.