Introduction: To determinate the etiology and risk factors for a first episode of cerebral ischemia in young adults at three hospitals of Lima and Callao-Peru. Methods: Multicentric study carried out at three national hospitals in Lima. The sample included 30 patients with a first episode of stroke and 60 controls matched by age and sex 2:1 with the patients. Serum biochemistry studies, EKGs and echocardiograms were done. Etiologies were classified based on the classification of Baltimore-Washington Cooperative Young Stroke Study. Results: The most frequent etiologies were cardiac embolism and atherosclerotic valvular heart disease, which were 30% of the cases (9 patients) each one. Hypertriglyceridemia (p. = 0.014), valvular heart disease (p. = 0.001) and hormonal contraception/replacement therapy (p. = 0.002) were independent risk factors for a first episode of cerebral ischemia in peruvian young adults. Motor deficiency was the most frequent presentation (50.0%). Intracraneal hypertension and urinary tract infection were the most frequent complications during acute ischemia and mortality was raised up to 10%. Conclusions: The hypertriglyceridemia, valvular heart disease and the use of oral contraceptives are independent risk factors for a first episode of ischemia in young adults from three hospitals of Lima and Callao. The most frequent etiologies were cardiac embolism and atheroesclerotic valvular heart disease. © 2009 Sociedad Española de Neurología.