The purpose of the study was to determine whether gender or race differences in ozone (O3) response exist among white and black, males and females, and to develop concentration-response curves for each of the gender-race groups. Three hundred seventy-two subjects (n>90 in each gender-race group), ages 18 to 35 yr, were exposed once for 2.33 h to 0.0 (purified air), 0.12, 0.18, 0.24, 0.30, or 0.40 ppm O3. Lung function and symptom responses were expressed as percent change from baseline and analyzed using a nonparametric two factor analysis of variance. Three primary variables were analyzed: FEV sub 1, specific airway resistance (SRaw), and cough. Statistical analysis demonstrated no significant differences in response to O3 among the individual gender-race groups.