Teratoma with a malignant somatic component (MSC) is a rare phenomenon recognized when a somatic type malignancy occurs in the context of a germ cell tumor (GCT). The authors present their 29-year experience with 40 patients treated from 1981 to 2009 in their institution. The average age was 31 years. All patients underwent radical orchiectomy, which demonstrated a GCT in 19 with an MSC. The MSC was observed in the other 21 cases in metastatic sites, including lung (13), liver (3), pleura (1), mediastinum (7), supraclavicular lymph nodes (1), and retroperitoneal lymph nodes (9). The most common histologic types were rhabdomyosarcoma (n = 11) and primitive neuroectodermal tumors (n = 10), followed by adenocarcinoma (n = 9), sarcoma, not otherwise specified (n = 5), well-differentiated liposarcoma (n = 2), leiomyosarcoma (n = 2), chondrosarcoma (n = 2), nephroblastoma (Wilms's tumor), carcinoid, malignant peripheral nerve sheath tumor, and a gemistiocytic astrocytoma with choroid plexus tumor (each n = 1). Clinical data were collected through a dedicated database and are available for all 40 cases. After a median follow-up of 37 months, 29/40 (72.5%) were alive and disease-free. Stage-specific survival was 100% for stage I, 87.5% for stage II, and 53% for stage III patients suggesting that patients with MSC confined to the testis have a good prognosis. A lower sensitivity to chemotherapy for a MSC when compared with typical GCT is reported. Surgical excision of the MSC is therefore an essential part of the management.