The serious form of alpha-1-antitrypsin deficiency (ATD) Pi ZZ strongly predisposes the individual for pulmonary emphysema and premature death in adulthood, especially if exposed to tobacco smoking. General screening of all new-born children was conducted in Sweden during 1972-1974, the major purpose being to reduce exposure of the child to parental smoking while growing up and to prevent the child from starting to smoke. Sixty-one children with ATD neonatally identified through mass-screening, and their families, have been compared with a demographically matched control group regarding smoking habits, as studied through interviews and questionnaires on two occasions. When the children were 5-7 years old, the smoking rates among parents of the ATD children and especially among the ATD fathers exceeded smoking rates for controls. Thirteen years later no differences in parental smoking were found between the groups. At 18-20 years of age the ATD children reported smoking significantly less than the control children (p < 0.05). From the perspective of prevention, the goal of the neonatal screening to reduce the smoking rates among the parents of the ATD children was not attained, while it was achieved among the ATD children. The results indicate that a screening program with early detection of ATD effectively prevents adolescent children from starting to smoke. From ethical, medical and psychological points of view, a voluntary screening program for ATD in pre-adolescence is recommended.