Single embryo transfer (SET) originated in Nordic countries and is well accepted in the rest of the world especially in Europe and Japan. Though the clinical situation is very variable, social security systems or reimbursement programs as well as newly introduced legislation or guidelines in these countries have effectively promoted SET in various ways. Recent findings suggest that there is no significant difference in the live-birth ratio between SET and multiple embryo transfer in certain clinical conditions. We should, therefore, encourage the move to SET, subject to informed consent from the patients.