卵黄囊瘤又称内胚窦瘤，来自多能原始生殖细胞，形态变化多样。其生物学行为表现恶性，预后很差〔１〕。我们收集了经病理诊断证实的３１例恶性卵黄囊瘤进行分析，现报告如下。１　临床资料３１例中肿瘤发生部位以卵巢最多，１５例（４８．３８％）；颅内６例（１９．３５％） Yolk sac tumors, also known as endodermal sinus tumors, are derived from pluripotent primordial germ cells with various morphological changes. Its biological behavior is malignant and the prognosis is poor [1]. We collected 31 cases of malignant yolk sac tumors that were confirmed by pathological diagnosis. The report is as follows. 1 Clinical data 31 cases of tumor occurrence in the most ovarian sites, 15 cases (48.38%); intracranial 6 cases (19.35%)