We report the case of a HIV-positive patient with teratoma malignant transformation in a retroperitoneal metastasis of testicular germ cell carcinoma, submitted to chemotherapy with complete laboratorial response and retroperitoneal lymph node dissection. The pathological analysis of the specimen demonstrated an admixture of non-germ cells within it (adenocarcinoma) with teratoma. Other primary malignancies were excluded. After 48 months, no disease recurrence or other primary neoplasm were diagnosed.