During the 36-month period from July, 1978, through July, 1981, 25 patients underwent a subxiphoid pericardial window procedure for diagnosis and therapy. Twelve patients were operated on for uremic pericarditis, 6 for malignancy, and 7 for etiological diagnosis of the pericarditis. All 12 patients with renal failure had enlarging effusions, despite aggressive dialysis. Eleven of the 12 are alive, free from recurrence, 3 to 36 months postoperatively. Six patients were operated on for suspected pericardial malignancy with hemodynamic compromise. Histological diagnosis was made from the pericardial tissue in all patients; only 1 patient lived more than 43 days following the procedure. In the group of 7 patients operated on for diagnosis, 4 were thought preoperatively to have tuberculous pericarditis. All 4 were treated with anti-tuberculosis chemotherapy and are asymptomatic, without evidence of calcification, 12 to 31 months postoperatively. This diverse group of patients demonstrates that the subxiphoid pericardial window is an effective approach for relief of uremic effusions and may adequately treat effusive tuberculous pericarditis when combined with multidrug chemotherapy. Patients with suspected malignant pericardial disease and hemodynamic compromise need to be carefully studied before an operative procedure is considered as a means of diagnosis and therapy.