There is a paucity of outcome data on patients with idiopathic pericardial effusion requiring intervention. All patients who had clinically significant pericardial effusion confirmed by echocardiography and requiring interventions between 1979 and 2000 were identified through the Echo-guided Pericardiocentesis Registry and Echocardiography and Surgical Databases. Clinical data and outcomes were obtained by review of medical records and surveys. The study population consisted of 92 patients (mean age 59 +/- 15 years). Five patients were referred directly for pericardiectomy (3 had effusion in the context of chronic relapsing pericarditis, 2 had effusive constrictive disease), and 87 underwent echo-guided pericardiocentesis as their initial treatment. In 47 of these patients, primary management involved extended pericardial catheter drainage, which was associated with a trend to lower recurrence rates than in those without catheter drainage (p = 0.052). Three patients had transient right ventricular entry with no sequelae, and 7 patients (8%) later had surgical pericardiectomy because of the recurrence of effusion, 2 of whom were also found to have evidence of effusive constrictive disease during surgery. One patient had bleeding after pericardiectomy that required repeat thoracotomy. Mean follow-up of the cohort was 3.8 +/- 4.3 years. For most patients with clinically significant idiopathic pericardial effusion requiring intervention, echo-guided pericardiocentesis was the definitive treatment. Pericardiectomy was necessary for patients in whom effusion occurred in the context of effusive constrictive disease, chronic relapsing pericarditis, or recurrent effusion despite pericardiocentesis. The prognosis for the cohort was favorable, and survival did not appear to differ from that of the general population (p = 0.372).