To determine whether routine preoperative pulmonary function tests provide useful prognostic information in orthotopic heart transplant candidates, we evaluated the pulmonary status of 33 patients who subsequently underwent transplantation. There was one perioperative death and five other fatalities within 9 months after operation. Mean age of the six patients who died (mean +/- SD 51.8 +/- 5.0 years) was significantly different (p less than 0.05) from that of the survivors (44.6 +/- 11.1 years). Mean preoperative pulmonary vascular resistance was significantly different (p less than 0.05) between those patients who had a fatal outcome (mean, 4.4 +/- 2.0 mm Hg/L/min) and those who survived (2.7 +/- 1.0 mm Hg/L/min). By contrast, we found that measures of forced vital capacity, forced expired volume in 1 second, diffusion capacity for carbon monoxide, and arterial blood gases bore no apparent relationship to outcome. We conclude that standard noninvasive measures of pulmonary function may be useful in preoperative preparation of heart transplant candidates, but they do not appear to be helpful in predicting eventual outcome.