To study the relationship between the distribution of pulmonary blood flow, pulmonary ventilation, and pulmonary capillary wedge pressure, we studied six patients with chronic congestive heart failure (CHF) (New York Heart Association classes II and III) at rest and during exercise. We used krypton 81m (81mKr) and technetium 99m (99mTc) to assess lung ventilation and perfusion at rest and during exercise. Hemodynamic measurements were obtained with a balloon floatation thermodilution catheter. At rest, the upper lung zones of patients with CHF received significantly higher proportions of the blood flow compared with previously published data in normal volunteers. During exercise, however, the fractional perfusion to apices did not change, which suggests that apical flow redistribution is already maximized at rest. Measured pulmonary capillary wedge pressure failed to correlate with the upper zone or the ratio of upper-to-lower zone perfusion counts. Our findings suggest that upper zone flow redistribution may be associated with high, normal, or low capillary wedge pressure and therefore does not correlate with the pulmonary capillary wedge pressure in patients with chronic CHF.