In vitro fertilisation (IVF) usually involves controlled ovarian stimulation (COS). There is now increasing emphasis on methods that make IVF safer and more patient-friendly. Modified natural cycle (MNC)-IVF is an example of this. In MNC-IVF spontaneous ovulation is prevented with a minimal amount of hormones and spontaneous monofollicular growth is supported. As a result, there is no risk of ovarian hyperstimulation syndrome, and the risk of a multiple pregnancy is low. There is a 9.1% chance of a pregnancy after one MNC-cycle and the cumulative pregnancy rate after a maximum of 6 MNC-IVF cycles is 33.4%. The cumulative results of a maximum of 6 MNC-IVF cycles are comparable to those of the first COS-IVF treatment cycle including transfer of cryopreserved embryos produced as a result of the treatment (33.4% versus 37.7%). The risk of a twin pregnancy following MNC-IVF is 0.1%, and 18.3% following COS-IVF. This means that MNC-IVF is a good alternative for COS-IVF.