Primary anterior mediastinal neoplasms account for 50% of all mediastinal masses with thymomas being the most common. These tumors demonstrate T1-20 1, Tc-99m sestamibi, and Tcc99m tetrofosmin uptake during SPECT myocardial scintigraphy A 60-year-old Filipino with hypertension, dyslipidemia and prior history of ischemic stroke underwent Tc-99m sestamibi SPECT dipyridamole stress. Inhomogeneous tracer uptake of the left ventricle in the inferior and inferolateral region was noted which was attributed to diaphragmatic attenuation. Gated SPECT showed normal myocardial thickening and wall motion. Extracardiac mediastinal activity was visualized on both the resting and stress images. Computed tomography scan demonstrated two (2) well-defined homogeneously enhancing lesions in the left anterior mediastinum most likely a thymoma. Specialists who interpret myocardial scintigrams should be aware of the causes of non-cardiac uptake so that unanticipated focal extracardiac accumulation during myocardial scintigraphy will lead to further investigation to establish the diagnosis of mediastinal tumors.