Treatment with exogenous gonadotrophic hormones to overcome certain cases of female infertility has been used for more than 30 years. Children born after such treatment have not shown any increased incidence of abnormalities (genetic or otherwise) and their reproductive ability seems normal. Furthermore, no increase in malignant disease (breast, ovarian, endometrial) have been reported following such repetitive gonadotrophic stimulations. Thus it seems the treatment can be regarded as safe. Two categories of patients are treated today. Firstly, hypothalamic-hypophyseal insufficiencies (WHO group I), where treatment is compulsory for attaining fertility, and secondly (including anovulation WHO group II), more or less regularly cycling women, where gonadotrophic treatment is used to augment fertility. Especially in the latter group, caution must be taken not to induce adverse effects. To meet these demands, exogenous gonadotrophic stimulation needs to be combined with other drugs and regimens that take into consideration the problems created by the concomitant presence of endogenous gonadotrophins.