Objective: To evaluate whether specific clinical or radiographic factors predict inferior vena cava (IVC) or abdominal aortic (AA) resection or reconstruction (RoR) at the time of postchemotherapy retroperitoneal lymph node dissection (RPLND) for germ cell tumors of the testicle. Materials and Methods: Two hundred seventy-seven patients undergoing postchemotherapy RPLND at two institutions between 2005 and 2015 were identified. Preoperative imaging was reviewed with radiologists blinded to operative details. Univariable and multivariable logistic regressions were performed, and a model was created to predict the need for great vessel RoR using radiographic and clinical factors. Results: Of 97 patients with preoperative imaging and clinical data available, 16 (17%) underwent RoR at RPLND. On univariable analysis dominant mass size, degree of circumferential vessel involvement, and vessel deformity were associated with RoR (all P <.05). No patients with clinical stage IIA or IIB disease at diagnosis required RoR. In the multivariable model, mass involvement of the IVC >135° (odds ratio 65.5, 7.8-548, P <.01) and involvement of the AA >330° (odds ratio 29.0, 3.44-245, P <.01) were predictive for RoR. These thresholds yielded a PPV of 48% and 50% and a NPV of 92% and 97% for IVC and AA RoR, respectively. Conclusion: Degree of circumferential involvement of the great vessels is an independent predictor for resection or reconstruction of the IVC or AA at postchemotherapy RPLND. Patients at high risk of great vessel reconstruction should be informed accordingly and have the proper teams available for complex vascular reconstruction.