A newborn male baby was transferred to our hospital with a left inguinal mass. The mass was huge measuring $10{ imes}10cm$, engorged, and dark-blue colored as a result of internal hemorrhage. Unstable vital signs were combined with DIC and acute renal failure. Emergency operation was performed because of the suspicion of bowel perforation. The peritoneal cavity was full of ascitis and the distal jejunum had a 0.5 cm perforation. Segmental resection of the jejunum and incisional biopsy of the inguinal mass were performed. On pelvic and thigh MRI, the mass protruded into pelvic cavity and encircled large vessels and nerves of the thigh. Pathologic diagnosis was congenital infantile fibrosarcoma. Fifteen days after operation, primary tumor excision was undertaken. The second look operation, performed after 6 times VAC chemotherapy, revealed no remained malignant cell on microscopic section. The baby has been followed closely for the last eight months.