Viable seminoma encountered at post-chemotherapy retroperitoneal lymph node dissection for pure testicular seminoma is rare due to the chemosensitivity of this germ cell tumor. In this study we define the natural history of viable seminoma at post-chemotherapy retroperitoneal lymph node dissection.The Indiana University testis cancer database was queried from 1988 to 2011 to identify all patients with primary testicular or retroperitoneal pure seminoma and who were found to have pure seminoma at post-chemotherapy retroperitoneal lymph node dissection. Clinical characteristics were reviewed and survival analysis was performed.A total of 36 patients met the study inclusion criteria. All patients received standard first line cisplatin based chemotherapy and 17 received salvage chemotherapy. The decision to proceed to retroperitoneal lymph node dissection was based on enlarging retroperitoneal mass and/or positron emission positivity in the majority of cases. Seven patients had undergone previous retroperitoneal lymph node dissection. Additional surgical procedures were required in 19 patients to achieve a complete resection. The 5-year cancer specific survival rate was 54%. However, only 9 of 36 patients remained continuously free of disease and of these patients 4 received adjuvant chemotherapy. Mean time from post-chemotherapy retroperitoneal lymph node dissection to death was 6.9 months. Second line chemotherapy, reoperative retroperitoneal lymph node dissection and earlier era of treatment were associated with poorer cancer specific survival.A total of 36 patients with pure seminoma were found to have viable pure seminoma at post-chemotherapy retroperitoneal lymph node dissection. While 5-year cancer specific survival was 54%, these surgeries are technically demanding and only a minority of patients achieves a durable cure from surgery alone.