Avoidance of multiple pregnancy without decrease of pregnancy rate is a challenge in ART. In 2005, we transferred an average number of 1.9 embryos, and the percentage of multiple pregnancies in double embryo transfer was 26.4% at our clinic, which was unacceptably high. In 2006, we introduced measures to avoid multiple pregnancy by decreasing the number of embryos transferred. In 2008, the average number of transferred embryos was down to 1.2 and the rate of multiple pregnancy was less than 5%. The pregnancy rate per embryo transfer was not lowered in 2008, compared with that in 2006. We found 4 factors which enabled us to reduce the multiple pregnancy rate while maintaining the pregnancy rate: blastocyst transfer instead of cleavage stage embryo transfer; frozen-thawed embryo transfer instead of fresh embryo transfer; selection of the patients who would benefit from the transferring of two embryos; and SEET (Stimulation of Endometrium Embryo Transfer) for blastocyst transfer.