Gastrointestinal stromal tumors (GISTs) are the most prevalent mesenchymal tumors of the gastrointestinal tract. GISTs are considered to originate from the interstitial cells of Cajal, the pacemakers of the peristaltic activity of the gastrointestinal tract. More than 95% of GISTs express KIT protein and discovered on GIST-1. GISTs may also be encountered in locations outside the gastrointestinal tract, in which case they are referred to as extra-GISTs (EGISTs) and often behave more aggressively. This is the case report of a primary pericardial EGIST in a 53-year-old male patient, confirmed by immunohistochemistry. To the best of our knowledge, this is the third case of EGIST diagnosed above the diaphragm, without being associated with the esophageal wall. Two cases of primary EGIST arising from the pleura were reported previously. In addition, this is the first reported case of an EGIST originating from the pericardium.