Prediction equations for DLCO and diffusing capacity per unit of lung volume (DL/VA) were generated from 245 normal subjects (122 women and 123 men) using a standardized technique for measuring DLCO. Measurements were made at an altitude of 1,400 meters. Multiple linear regressions were made using standard and robust regression techniques. The resultant equations predicted values for DLCO and DL/VA that were higher than most previously reported values. The use of robust regressions did not add to the predictability of standard linear regressions.