True superficial temporal artery (STA) aneurysms are extremely rare and usually atherosclerotic in origin. Here the authors report a 62-year-old man with a nonpulsatile mass lesion at the trace of the right STA that was surgically excised with a preoperative diagnosis of subcutaneous mass lesion, preoperatively and histopathologically found out to be a thrombosed true STA aneurysm. Preoperative evaluation, differential diagnosis, and management of such lesions are discussed.