In recent years, many aspects of juvenile stroke have been addressed in medium-sized case series. We have analyzed stroke severity, etiology, risk factors, and outcome in different age groups in the large dataset of the Austrian Stroke Unit Registry. In the nationwide Austrian Stroke Unit Registry 13,440 men and women with ischemic stroke or transient ischemic attack were recorded between March 2003 and February 2007. A number of important disease characteristics were documented by a stroke specialist upon admission of a patient and at discharge from the stroke unit and during a 3-month follow-up interview. A total of 749 patients (5.6%) were 18 to 45 years old and 1895 (14.1%) 18 to 55 years. Arterial dissection and cardiac/paradoxical embolism were the most common causes of stroke up to an age of 45. With a steeply increasing frequency of standard vascular risk factors, micro- and macroangiopathic causes of stroke substantially gain weight after the fourth decade of life. At 3-month follow-up, good clinical outcome (mRS 0-2) and death were 88.3% and 1.4% in the young (<or=55 years), and 65.3 (9.2%) in subjects aged 56 years and over. In multivariate analysis, young age (<or=55 years) predicted a good clinical outcome (Odds Ratio [95% confidence interval] 3.4 [2.4-5.0]) independently from stroke severity (NIH-SS), concomitant risk factors, stroke etiology, and thrombolytic therapy. Young men experience a significant delay in the onset-to-door time in comparison to other segments of the population. Increasing awareness about the relevance of stroke in the young is a valuable target for future health campaigns.