Pulmonary function was assessed by spirometry in 5,201 ambulatory elderly participants of the Cardiovascular Health Study, sampled from four communities. A stringent quality assurance program exceeded American Thoracic Society (ATS) recommendations for spirometry. Less than 6% of the participants were unable to perform three acceptable spirometry maneuvers. A "healthy" subgroup of 777 women and men 65 to 85 yr of age was identified by excluding smokers and those with lung disease and other factors determined to independently, significantly, and negatively influence the FEV1. Results from black participants were examined separately. Reference equations and normal ranges for FEV1, FVC, and the FEV1/FVC ratio were determined from the healthy group. The results demonstrate differences in predicted values as great as 20% (0.5 to 1 L) for elderly patients when compared with the spirometry reference equations that are most commonly used in the United States.