The presence of renal cell carcinoma within a solitary kidney and vena cava extension presents complex management and surgical decisions for the treating urologist. To the best of our knowledge, we present the first case of partial nephrectomy and level II caval thrombectomy within a solitary kidney. Accessory renal veins were identified preoperatively using a three-dimensional, multidetector row computed tomography scan and preserved intraoperatively, allowing complete oncologic resection without compromising renal function.