After many years of use and a large number of publications there is still no good evidence to indicate that progestogens have a valid role in the treatment of patients with a history of abortion. In many of the published series the amount of material administered has been inadequate in the light of current concepts of progesterone secretion in pregnancy (Zander, 1959) and inadequate control observations have invalidated much published data. To assess the salvage rate in treated pregnancies and then compare it with that found for previous untreated pregnancies in the same patients ignores the number of pregnancies that would have reached viability if no treatment had been given at all. Malpas (1938) produced a theoretical estimate that any woman with a history of three consecutive abortions. . .