Prediction equations is forced vital capacity (FVC), forced expiratory volume in 1 second (FEVi), maximum mid-expiratory flow rate (MMFR) and peak expiratory flow rate (PFR) have been derived from a study of 367 asymptomatic Caucasian and Coloured (mixed race) children, aged 11--15 years, who did not smoke. Significant ethnic differences were found in FEVi, FVC, FEVi/FVC, and MMFR/FVC, but not in MMRF or PFR. The practical and epidemiological value of these observations is discussed.