During hospitalization for evaluation of a large testicular tumor with extensive metastatic disease, this 14-year-old boy collapsed while showering and could not be resuscitated. At autopsy, there was no evidence of thromboembolic phenomenon, a known cause of sudden death in metastatic testicular tumors and other large abdominal tumors. However, marked compression of the inferior vena cava by a large pelvicoabdominal tumor mass and findings suggestive of systemic-portal shunting were consistent with the death due to the impaired venous return via the inferior vena cava.