Hemorrhagic pericardial effusion is a rare presenting sign of undiagnosed rheumatoid arthritis (RA). We present a case of a 58-year-old female with a history of mucinous cystadenoma with subsequent omental caking status-post small bowel resection, chronic intermittent bilateral knee pain, carpal tunnel syndrome of the left hand, and drainage of a peritoneal inclusion cyst two days prior to admission. The patient had pleuritic chest pain and acute-onset shortness of breath but was hemodynamically stable on presentation. Transthoracic echocardiogram and CT scan demonstrated a large pericardial effusion measuring 1.5 cm anteriorly, 2.21 cm posteriorly, and 2.5 cm laterally. Diagnostic pericardiocentesis revealed a hemorrhagic pericardial fluid with a glucose level of 133 mg/dL, pH of 7.34, albumin of 2.6 g/dL, red blood cell count of 401,000 cells per cubic millimeters (CUMM), white blood cell count of 1,400 CUMM, lactate dehydrogenase (LDH) of 930 U/L, and protein of 5 g/dL. Infectious and malignancy workups were negative. Rheumatologic workup was positive for elevated rheumatoid factor and anti-cyclic citrullinated peptide. The patient was diagnosed with RA; she was started on methotrexate with folic acid, and a pericardial drain was kept in place for three days. We present a brief review of the workup, etiologies, and therapeutic approach for patients who present with hemorrhagic pericardial effusion secondary to undiagnosed RA.