Danazol, an interesting pharmacologic steroid 'in search of a disease', was first used by my group in the management of endometriosis because of the marked anti-endometrial effects found during clinical trials. The results in alleviating dysmenorrhoea, dyspareunia, and pelvic discomfort were surprisingly good, but more important was the 40 to 50% pregnancy rate that occurred following discontinuation of its use. In addition, because we suspected that women with unexplained infertility might be harbouring an occult or microendometriosis, a 3 month course of 200mg of danazol was tried in such patients, and proved effective in overcoming infertility in roughtly 40% of patients within 6 months after discontinuation of medication. We serendipitously found that some habitual aborters carried to term after a course of danazol. Accordingly, a trial of 100mg daily for 3 months was undertaken with a satisfactory outcome in more instances than could be attributed to chance alone. To readily appreciate the effectiveness of this agent, one must be aware that conceptions may follow the use of placebos or whatever regimen is employed in about 15 to 20% of infertile women. The unusually good results that we and other investigators in the field obtained with danazol rules out a placebo effect.