Pulmonary arterial hypertension (PAH) is a serious condition that can lead to right heart failure and death. Pericardial effusion in PAH is associated with significant morbidity and mortality, and its pathogenesis is complex and poorly understood. There are few data on the prevalence of pericardial effusion in PAH, and more importantly, the management of pericardial effusion is controversial. Current literature abounds with case reports, case series, and retrospective studies that have limited value for assessing this association. Hence, we summarize the available evidence on this ominous association and identify areas for future research.