Reference spirometric values for vital capacity (VC), forced expiratory volume in one second (FEV1), forced vital capacity (FVC), forced expiratory volume in one second as percentage of vital capacity or of forced vital capacity (FEV%), the highest flow during forced inspiration (Vmax insp), the highest forced expiratory flow at 50% vital capacity (Vmax 50%), the highest forced expiratory flow when 75% of vital capacity has been expired (Vmax 25%), Vmax insp/Vmax 50% and peak expiratory flow (PEF) were determined in a series of 296 males and 257 females, 18-65 years old, who have never smoked. Equations were derived using height and age as predictors. The reproducibility was tested.