Prevalence and evaluative opinions about smoking among 527 adolescents and young adults were quantified in order to assess the efficacy of Thailand's mass media antismoking campaign. The reactions of subjects to the smoking of (a) father, (b) mother, (c) boys, (d) girls, and (e) myself were obtained using a semantic differential measure. Virtually all subjects had seen antismoking adds on television and the overall perception of smoking was highly disapproving with significant gender and age differences being present. Older males were more likely to smoke and had less critical attitudes about this harmful behavior than their younger peers and female participants. Reactions to female smoking (mother and girls) were more derogatory than to the same behavior among males (father and boys). Results suggest that smoking will continue as a serious problem among Thai males and demonstrate the addictive nature of cigarette smoking which persists in spite of the increasingly negative evaluative attitudes of users.