Smoking during pregnancy is harmful to the health of the fetus and the newborn. Smoking increases the risk of low birthweight, preterm delivery and perinatal death. In developed countries smoking during pregnancy is regarded as the single most important risk factor for which it is possible to intervene. We reviewed the Scandinavian and English randomized controlled intervention studies directed towards smoking cessation during pregnancy. The intervention studies were classified according to the method of intervention namely antismoking advice, self-help manuals, measurements of smoking dependent chemical factors and multifactorial methods. We conclude that it is possible to reduce smoking during pregnancy only by an efficient and personal effort performed by a committed person towards each pregnant woman.