Objective: To survey drug use by breastfeeding women, and to compare this with nonbreastfeeding women. In addition, we were interested whether drug use was of influence on the decision to give breastfeeding, and the other way around. Design and setting: During a 6-week period in 2002, a questionnaire was handed out to all women with a child not older than 6 months, who visited a Well-Baby Clinic in the province of Friesland, the Netherlands, eventually resulting in 549 returned questionnaires (response 43%). Results: In all, 82.1% of the participants breastfed their baby at least at any time during the first 6 months after birth. More than half (65.9%) of all breastfeeding women had used drugs; however, they used drugs less frequently than nonbreastfeeding women (79.6%). The pattern of drug use differed: oral contraceptives, iron preparations, drugs for peptic ulcer, and several psychotropic drugs were more frequently used by nonbreastfeeding women, while vitamins were more frequently used by breastfeeding women. Drugs play an important role in women's decision to start or continue breastfeeding: women frequently hesitated to use drugs during breastfeeding, stopped either breastfeeding or drug use to avoid combining the two, took a measure to minimise exposure to the child, did not use any drug because of breastfeeding, or did not breastfeed because of drug use. Conclusions: Drugs are frequently though reluctantly used during breastfeeding, and play an important role in the decision to start and stop breastfeeding. Information how to deal with drugs seems therefore indispensable in efforts to promote breastfeeding.