A Pericardial Friction Rub rub refers to a perceptible clinical marker utilized to establish the presence of Pericarditis. During auscultation, the doctor may notice an additional heart sound of back and forth quality, classically, along with three elements, one occurring in systole and the other two occurring in early and late diastole. Best heard between the apex and sternum, specifically the lower left sterna border, the sound can be similar to high-pitched leather-sounding grate or scratch. Due to its high frequency, the sound can be best listened to when the patient leans to the fore or lies supine with fixed pressure on the diaphragm of the stethoscope.

This is associated to some inflammation in the pericardium. Typically, the parietal and visceral layers contain a slight amount of pericardial fluid, however, with the existence of an inflamed pericardium, the walls are pressing against each other with resultant audible friction.

Patients with pericardial friction rub are expected to experience sharp pressing pain on the chest.