We assessed lung function, liver function, and smoking attitudes and behavior in 22 adolescents with homozygous alpha 1-antitrypsin deficiency whose condition had been detected through neonatal screening in the early 1970s. All subjects had normal lung volumes, expiratory flow rates, and diffusing capacity except for two siblings with mild asthma whose values reverted to the normal range after administration of an inhaled bronchodilator. Liver function was normal in all subjects with the exception of one boy who had an isolated elevation of alkaline phosphatase activity. Smoking attitudes, as determined by questionnaire, did not differ from those of 130 control subjects, but smoking initiation rates were significantly lower (p = 0.02). We believe that the issue of neonatal screening for alpha 1-antitrypsin deficiency should be reexamined because augmentation therapy for adults with emphysema is now available, and screening followed by family-based smoking intervention may lead to a nonsmoking life-style. The latter is especially important because the current weight of epidemiologic evidence strongly suggests that in nonsmokers with this condition, severe emphysema may never develop or, if it does, it will do so at a much later age than in smokers.