e15621 Background: Thromboembolism (TE) accounts for significant morbidity and mortality in cancer patients. Rates of TE have been reported from 0.9%-28.0%, depending on the population. Patients with germ cell tumors have a 4.0-8.4% risk of TE following platin chemotherapy. Our patients are high-risk, many with advanced disease receiving high-dose chemotherapy and peripheral blood stem cell rescue. We sought to more completely understand TE events in advanced germ cell tumor patients. Methods: Forty-four consecutive patients visiting our germ cell tumor clinic between 11/05/2012 and 1/22/2013 were selected. Data were collected by retrospective chart review from tumor diagnosis until TE (ranging from TE on diagnosis to 20 years later). A logistic regression model was fitted to determine variables that predispose patients to TE. Results: In our patient series, seven (15.9%) had venous TE and none had arterial events. Five patients (11.4%) had TE within 16 weeks of chemotherapy, and 2 at 10 and 19 years after diagnosis, respectively. Two had bilateral pulmonary emboli (PE) (4.5%), 3 had upper or lower extremity DVTs, or both, and 1 had bilateral PE and DVTs. Five patients with TE had nonseminomatous tumors, 2 had non-testis primaries, 4 had relapsed disease, 2 with late relapse (>7 years), 6 had metastatic disease, 3 had retroperitoneal lymph node dissection, and all 7 received platin chemotherapy. In logistic regression analysis, significant risk factors for TE included relapse (P= .016), bulky retroperitoneal lymphadenopathy (P= .006), alpha-fetoprotein >10,000 (P= .047) beta-HCG > 1,000 (P= .020), chemotherapy (P= .031), platin-refractory disease (P= .055), and poor risk disease compared to good risk disease (P=.020). Conclusions: Germ cell tumor patients have a high risk of venous TE. Those with relapsed disease, bulky retroperitoneal lymphadenopathy, platin chemotherapy, platin-refractory, or poor risk disease are at increased risk. Our estimates are higher than previously reported and in contrast to earlier studies, do not include arterial TE. To confirm our findings, we will extend this study to 100 patients. If confirmed, this pattern of TE events may be a consequence of advanced stage disease in our patients.