Maternal smoking during pregnancy causes significant fetal morbidity and is a public health problem, as 36% of women in the UK and 11% of those in the US smoke during pregnancy. Behavioural support for smoking cessation, provided outside of routine antenatal care, is effective for promoting smoking cessation by pregnant women, but relatively few pregnant women access such support. Effective pharmacological aids to smoking cessation, which have been trialled in nonpregnant populations, include nicotine replacement therapy (NRT), bupropion and varenicline; however, there is very little evidence to justify the use of these drugs in pregnancy. Also, for safety reasons, it is doubtful that definitive trials investigating the effectiveness of either bupropion or varenicline for smoking cessation will be conducted in pregnant women in the foreseeable future. In the short to medium term, research information relating to the use of these drugs in pregnancy is, therefore, likely to be derived from observational studies that are more difficult to interpret than clinical trials. This article assesses the evidence for the effectiveness and safety of using NRT, bupropion and varenicline for smoking cessation during pregnancy. The principle recommendations made are that NRT may be safer than smoking in pregnancy, and pregnant women who have unsuccessfully tried to stop smoking without pharmacotherapy may consider using NRT in subsequent quit attempts after informed discussion with their doctor. There is no evidence, however, that NRT is actually effective for smoking cessation in pregnancy. With currently available evidence, bupropion and varenicline cannot be recommended in pregnancy for smoking cessation.