Testicular cancer is one of the most common cancers diagnosed in young men. Frequent sites of metastasis include the retroperitoneum, lungs, liver, brain, and bone. Intra-cardiac metastasis has also been described. An 18-year-old boy with a history of mixed testicular germ cell tumor presented to our institution for surgical resection of his metastatic disease. Intraoperative transesophageal echocardiography during his surgery confirmed a tumor thrombus into the left atrium coming from the left pulmonary vein. We report a case of metastatic testicular cancer with rare tumor extension from the left inferior pulmonary vein into the left atrium. Perioperative transesophageal echocardiography was necessary to aid intraoperative diagnosis and confirmation of the intracardiac tumor, providing data to guide surgical strategy.