Analyses in this study were based on hemodynamic and angiographic data obtained in a cohort of 1,371 predominantly black patients during right and left heart catheterization. All patients were followed up prospectively for a mean of 117 weeks, and 103 fatal events were recorded. In Cox survival analysis, three variables were found to be independently related to survival: pulmonary artery mean pressure (PAMP), number of stenosed vessels, and left ventricular (LV) ejection fraction (p less than 0.01); in multivariate stepwise analysis, PAMP entered the model first with the largest chi 2 value of the three prognostic variables (chi 2 = 33.4; p less than 0.0001). The PAMP was 32 percent higher in decedents compared with survivors (25 + 11 mm Hg vs 19 + 8 mm Hg, p less than 0.01 [mean, SD]) and a 10 mm Hg increase in PAMP was associated with a more than fourfold increase in the relative risk of dying; this finding was independent of pulmonary vascular resistance and therefore could not be attributed to primary pulmonary vascular or parenchymal disease. In both the subgroup of 1,118 patients with a normal LV ejection fraction (greater than 50 percent) and the 253 patients with a reduced ejection fraction (less than 50 percent), PAMP emerged as an independent predictor of mortality (p less than 0.0001 and 0.01, respectively), and is therefore a marker of cardiac disease beyond impairment of systolic contractile function. Among patients without obstructive coronary artery disease, PAMP alone provided prognostic information in the multivariate survival analysis.