Extra-skeletal osteosarcoma (ESOS) is a rare mesenchymal neoplasm characterized by osteoid production that arises in the soft tissue, accounting for 1% of soft tissue sarcomas and 5 % of osteosarcomas. There exists little data on the management of ESOS, and the overall survival prognosis remains poor. As for all sarcomas, surgical resection is still the primary curative treatment for ESOS. Whether patients with ESOS should be treated using the multimodality therapy for soft tissue sarcomas or the one used for osteogenic sarcomas is being debated. Our case reports the management and outcome of a 40 year-old man treated for a large retroperitoneal ESOS in the infrarenal aortocaval window. The patient had neoadjuvant chemotherapy with 6 cycles of Doxorubicin and Ifosfamide, followed by external beam radiation (total dose of 50.4 Gy over 6 weeks). Six weeks later, the patient had successful definitive surgical resection of ESOS, and was discharged home on post-operative day 7. At 6 months follow-up, the patient is well without complaints, and has no evidence of recurrent disease. In the video, we show the en-bloc surgical resection of the large retroperitoneal ESOS, including segments of the inferior vena cava and aorta. Aortic and caval graft reconstruction are demonstrated.