To evaluate the prevalence of illegal drug use, smoking and alcohol consumption in Irish primigravidas, we interviewed 1011 women at their booking visit. A total of 23.5% (235) of women had used illegal drugs prior to their first pregnancy, 28.9% were ex-smokers and 27.9% were still smoking during pregnancy. A total of 53.9% admitted to drinking alcohol during pregnancy. Smokers are 2.8 times more likely to have used drugs in the past than non-smokers. Level of alcohol consumption appears to be a significant predictor of drug use.