Every practitioner active in the field of assisted reproduction treatment is aware of the risks and complications related to twin and higher-order multiple pregnancies. Introduction of single embryo transfer (SET) into IVF/intracytoplasmic sperm injection (ICSI) is one of the possible ways of reducing the rate of twin pregnancy. Careful selection of patients, in combination with elective SET, has been shown to decrease the twin pregnancy rate while maintaining a stable ongoing pregnancy rate. The combination of a woman younger than 38 years of age, in her first or second IVF/ICSI cycle and with an embryo with a high implantation potential is the key to successful SET. This article will discuss embryo selection and patient selection and review the data published on SET. In the Centre for Reproductive Medicine at Middelheim Hospital, 39% of all transfers in 2002 were SET; the ongoing pregnancy rate remained stable at 30.6%. The twin (multiple) pregnancy rate declined to 11.7%. Particular attention should be drawn to the augmenting effect of the pregnancy rate of frozen-thawed cycles. Health economic data available so far subscribe the plea for SET.