The objective of the study was to assess the frequency of alternative medical usage in an antenatal population. A survey of alternative medicine usage was carried out among 305 consecutive patients over 2 months at their registration in mid-pregnancy at an Australian Antenatal Clinic. The study showed that something like 40% of patients used alternative medical therapy, including 12% herbal therapy. No specific study of pregnancy outcome was carried out, but it is of concern that some herbs taken had the potential to adversely affect pregnancy outcome. The herbal therapies commonly used in pregnancy are reviewed with their potential complications; examples of toxicity are also discussed. It is important to obtain a herbal medicine history at any time but particularly in pregnancy. Herbs may have unrecognised effects on pregnancy or labour, have interactions with prescribed medications and have potentially serious complications for the foetus.