The impact of aging on pulmonary hemodynamics was investigated in 322 patients who underwent right- and left-sided cardiac catheterization and echocardiographic examination, and were free of coronary disease, impaired left ventricular systolic function and left ventricular dilatation. Most of the patients were black (83%) and hypertensive (78%). Mean pulmonary artery pressures increased progressively with age: 16.7 +/- 4.6, 17.9 +/- 6.4 and 20.6 +/- 8.0 mm Hg for those aged less than 45 (n = 50), 45 to 64 (n = 238) and greater than or equal to 65 years (n = 34), respectively (p = 0.020). Pulmonary vascular resistance was 99 +/- 42, 116 +/- 62 and 160 +/- 68 dynes s cm-5, and the ratio of pulmonary to systemic vascular resistance was 78, 80 and 105%, respectively, for the 3 age groups (p less than 0.001). Along with these changes, a decrease in cardiac output and an increase in systolic blood pressure and systemic vascular resistance with age were noted. The effect of age on mean pulmonary artery pressure and pulmonary vascular resistance was statistically significant after adjustment for gender, smoking status, body weight, left ventricular hypertrophy, systolic blood pressure and systemic vascular resistance. Consideration should be given to age-related changes in the pulmonary circulation when defining physiologically normal values.