Group Name: Background and Aims: Ischemic stroke in young adults presents different risk factors profiles. The aim of the study was to establish the risk factors in young adults with stroke with large vessel atherosclerosis and vertebral artery hypoplasia. Methods: Medical records of 1687 patients with ischemic stroke from January 2018 till December 2019 were retrospectively evaluated and 56 patients aged 50 and less were selected. Was analyzed the risk factors profile, clinical presentation, neuroimaging, and comorbidities stratified by the presence of large vessel atherosclerosis and vertebral artery hypoplasia. Results: There are no differences between groups according to age, length of hospital stays, and NIHSS at admission. When stratified according to the presence of large vessel atherosclerosis the risk factors profile was like in older ages (fig. 1) with more important vascular ones. The second stratification (according to the presence of vertebral artery hypoplasia) the risk factors profile presented in fig. 2. In the group of patients with vertebral artery hypoplasia there are more recurrent strokes, located in the brainstem and less leukoaraiosis on imaging but not statistically significant. The statistical significative remains just the presence of atrial fibrillation and history of cardiovascular events. Conclusions: The risk factors profile is dominated with vascular factors in young adults with ischemic stroke with large vessel atherosclerosis compared to those with vertebral artery hypoplasia when remain statistically significant just associated atrial fibrillation and history of cardiovascular events, which are not directly related to the hypoplasia. More studies are needed to explain the findings. Trial Registration Number: 20.80009.8007.39