The case of a patient with an undifferentiated metastatic cardiac sarcoma is presented. A thallium-201 tumor study was performed to evaluate lung nodules. Thallium-201 chloride was injected intravenously and whole body images, as well as single photon emission computer tomography (SPECT) imaging of the chest, were obtained and reconstructed. They were displayed in three planes and then reconstructed again in cardiac planes. Multiple unsuspected metastases were found in the lower extremities. Viable tumor was demonstrated in both cerebral hemispheres. The lung nodules were not clearly identified. However, cold areas in the myocardium were detected corresponding to the findings on magnetic resonance imaging (MRI). In retrospect, at least one abdominal metastasis was identified. Whole body tumor imaging plays an important role in finding unsuspected primaries and in staging neoplasms to optimize patient care.