Considerable differences in the regulatory oversight of preimplantation genetic diagnostic (PGD) services exist among countries, ranging from total bans on any embryo manipulation to the almost complete absence of any regulations or authority. A survey of centres offering PGD services revealed common concerns about the creation of embryos for research, altering the pattern of normal embryo development and the potential for misuse in the clinical application of PGD. Copyright © 1998 John Wiley & Sons, Ltd.