During the last twenty years the incidence of ectopic pregnancies has doubled or tripled. They constitute about 1.13% of all pregnancies in Norway, and remain an important cause of subsequent infertility. The main risk factors are sexually transmitted diseases, pelvic inflammatory disease, and use of intrauterine device. This paper reviews some of the recently published epidemiologic and non-epidemiologic reports that have shown a positive association between ectopic pregnancies and cigarette smoking. Some ectopic pregnancies would probably be prevented if pregnant women refrained from smoking.