Everyone involved in obstetric practice at the present time will be well aware of the complexities of drug interactions in the mother and fetus, and in the newborn baby. Perhaps themost spectacular manifestations of these drug interactions are those that result in teratogenic effects, but the implications of drug therapy generally in pregnancy range far wider than the hazards of inducing fetal malformation. It must also be realised that there are hazards in withholding some therapeutic agents from pregnant women, and these hazards have to be weighed against the dangers of indis criminate drug therapy. It is often very difficult to obtain relevant information about any given compound in relation to its use in pregnancy, and it is therefore appropriate to provide a handbook which brings together information about a wide variety of drugs in a form which allows ready access for the practising clinician. Rodney Ledward first discussed this project with me some years ago, and it seemed to me at the time that with his background as both a pharmaceutical chemist and an obstetrician that his talents were particularly well suited to this task. In conjunction with Professor Hawkins, he has produced a concise reference book for use in clinical practice, which I feel confident will prove to be invaluable to all those practising obstetrics at all levels of seniority. . The book covers the use of drugs during pregnancy, but it also includes sections on the transfer of drugs into breast milk.