In Norway, the efficacy and the efficiency of IVF treatment for infertile couples have been questioned. Information about this topic is important for the general public, the infertile population, the gynaecologists and the health authorities. We have followed a cohort of 485 infertile couples accepted for in vitro fertilization treatment. During a 14 month period starting 1 January 1989 a total of 214 women have either delivered or are pregnant in the second or third trimester. This number represents 44% of the 485 women accepted for IVF treatment, irrespective of whether they were treated or not, and 50% of the couples who completed at least one IVF cycle. There was no difference in cycle efficiency (pregnancy rate) between the first to third cycle, but this was significantly lower in cycle 4-6. There was no difference in delivery rate between groups of patients with different diagnoses of female infertility, but an additional male factor reduced the delivery rate significantly. Replacement of cryopreserved/thawed embryos gave a 5% increase in the delivery rate per couple included in the study, and an increase of 13% in the number of deliveries.