Fifty six patients with yolk sac tumor are registered in the "Instituto Nacional de Enfermedades Neoplásicas" (Lima-Peru), from 1952-1980: 48.22% were less than 2 years of age; 51.78% were beyond that age.- Seventeen patients survived 3 years post diagnosis: 44% when patients less than 2 years of age and 17.2% when over two years of age. 25.9% of the patients less than 2 years of age were found to have metastases whereas 48.5% when over 2 years of age. 21/56 already had metastases when first seen. All tumors were greater than or equal to 3 cm. in diameter when first seen. Metastases were found in 38% of cases when tumors were less than or equal to 6 cm., compared to 61.9% of cases in which tumors exceeded 6 cm. 51.8% of clinical stage I survived 3 years without evidence of disease; 14.3% when stage II while none survived at clinical stage IV. It is to be expected that young patients who survive 3 years after diagnosis and treatment will not suffer a recurrence of the disease.