Approximately 30% of patients with disseminated testis cancer who receive platinum-based chemotherapy will experience normalization of tumor markers but have persistent, radiographically evident disease in the retroperitoneum. These patients usually undergo retroperitoneal lymph node dissection. Of 557 patients undergoing post-chemotherapy retroperitoneal lymph node dissection at our university medical center 45 (8.1%) had neoplastic elements distinct from the classical germ cell tumor types within the resected specimens. Examples include various sarcomas in 19 patients (3.7%), other nonsarcomatous nongerm cell cancers in 18 (3.2%) and cystic atypical choriocarcinoma in 8 (1.4%). No distinct patient characteristics or histological patterns in the primary tumor are predictive of these unusual findings in the retroperitoneal lymph node dissection specimen, although sampling error in the orchiectomy specimen could be the reason for this lack of correlation. Surgical resection of these chemoresistant tumors is potentially curative, with disease-free survival in 13 of 19 patients (68.4%) with sarcoma, 10 of 18 (55.6%) with nonsarcomatous cancer and 7 of 8 (87.5%) with cystic atypical choriocarcinoma at a mean followup of 30.6, 42.5 and 24.7 months, respectively.