This paper examines the current status of in vitro fertilization and embryo transfer (IVF-ET) as a treatment for various types of infertility. We reviewed studies on the efficacy and safety of IVF-ET and intracytoplasmic sperm injection (ICSI) plus IVF-ET, compared with conventional treatment or no treatment for various infertility diagnoses. Material retrieved included English language publications between 1992 and January 1997 that reported the results of prospective controlled clinical trials, cohort studies, and retrospective comparative studies with large series, and reviews presenting risks, complications, and longer-term health consequences associated with IVF-ET and ICSI. No adequate prospective comparative studies of sufficient power on the use of IVF-ET for specific infertility diagnoses have been reported to date. Most of the published reports concerning results with IVF-ET as a treatment of infertility have been based upon small, uncontrolled studies, with various methodological weaknesses. Reported results are not directly comparable. There are few follow-up data on outcomes after pregnancy is established or on long-term health consequences of the use of IVF-ET on mothers and their babies. IVF-ET has diffused widely without comprehensive assessment of its efficacy and safety. The available evidence supports its use only for severe bilateral tubal occlusion. For other diagnoses of infertility the evidence is limited and does not establish whether IVF-ET is effective. Long-term, well-designed, prospective clinical trials are required to determine when and for what indications IVF-ET is effective and what its health effects are on both mothers and their babies.