Summary The treatment of infertility contributes little to the world population problem. It is more likely to be helpful due to the stimulus it gives to general work in the field of reproduction and particularly in such aspects as the control of ovulation. There are two main types of female infertility (1) relative infertility , where pregnancy occurs but cannot be carried to a successful conclusion and (2) absolute infertility , where no pregnancy occurs. The combined incidence of these types of infertility is in the region of 20 per cent. Investigations should be undertaken to determine (1) the occurrence of ovulation, (2) the patency or otherwise of the fallopian tubes, and the development of the endometrium, and (3) the presence of cervical mucus which will not inactivate sperm. Ovulation can be detected by a variety of methods, the only two direct ones being visualisation of the ovum or the occurrence of a pregnancy. Patency of the fallopian tubes is best established by laparoscopy, but a combination of this with hysterosalpingography is necessary to eliminate uterine abnormalities. Uterine abnormalities, an incompetent cervix and possible corpus luteum deficiencies are important causes of relative infertility. The treatment of the first two conditions is surgical, and the results are generally good. Corpus luteum deficiency is not yet definitely proven, but new hormone assay techniques have become available which may help to eludicate this question. Tubal blockage can be repaired in some cases either by cornual implantation or by anastomosis. In selected patients amenorrhoea may be treated either by clomiphene or by gonadotrophins. It is not essential to monitor clomiphene treatment with hormone assays but this is mandatory in the case of gonadotrophin therapy in order to avoid the hyperstimulation syndrome. The ovulation rate with treatment is approximately 70 per cent. Releasing hormones are being used in infertility, but work is still at an early stage. Clomiphene and gonadotrophin therapy can be used in the treatment of anovulatory menstruation and also in apparently normal women who are infertile and who have abnormal hormone levels in the plasma during the menstrual cycle.