Stroke is the second leading cause of death in the world. Young stroke is considered at an age of less than 45 years. The incidence of young stroke ranges from 7 to 15 in 100,000 people per year. This incidence has substantially increased and adds to the cost of long-term care, posing a huge challenge to the health care system. As with stroke in normal adults, causes of stroke in the young also include large artery atherosclerosis, cardioembolic, small vessel disease, other determined etiology, and undetermined etiology. Identification of rare causes of young stroke requires a major diagnostic effort. Which diagnostic test is necessary for each patient is a matter that needs to be decided individually. Among the other determined and undetermined etiologies, non-atherosclerotic vasculopathy and genetic stroke syndromes constitute the major causes of stroke. Young females are more predisposed to migraine with aura, vascular disorders, and autoimmune conditions. Ethnic disparity also exists in this subset of the population. Lifestyle choices (cigarette smoking, drug abuse, and a sedentary lifestyle) can significantly increase the rate of stroke among the young. Causes of stroke in the young are often missed. With advances in science, it has become easier to detect genetic causes of stroke, as they have different management and their prognosis varies.