Paradoxically, the attitude of infertility patients towards multiple births has never been investigated. We therefore generated a survey by questionnaire, which was sent to 3800 consecutive unselected couples with infertility problems: 582 responses were received (15% response rate) and analysed. The percentage distribution of the responses to 21 questions, addressing attitudes towards and knowledge about the risk of multiple gestations, was the main outcome. Worry about multiple births was expressed, independent of the number of multiples, although fear about multiple conceptions was rejected by a large majority (64%). The risk of a twin birth was not strongly perceived, but the perception of risk increased with increasing numbers of multiples: triplets (50-62%), quadruplets or more (71-72%). A desire for the conception of twins was expressed by 67-90% of couples, a desire for the conception of triplets was equally expressed and rejected, and for a multiple gestation beyond triplets was rejected by 73-82% of couples. Patients were educated about the risks of selective embryo reduction and responded in a bimodal fashion to the option of utilizing this procedure, with equal numbers being willing to consider or reject it. Age, parity and length of infertility did not affect the couples' worry or fear about multiples. The desire for twins and triples, however, was correlated significantly with age (twins, P = 0.032; triplets, P = 0.03); there was no such correlation for larger multiples. The length of infertility was correlated with a positive attitude towards multiples beyond triplets (P = 0.029) but was not correlated with a desire for twins or triplets. Prior parity did not affect the attitude towards multiples at all.(ABSTRACT TRUNCATED AT 250 WORDS)