Commercial ELISA kits for the determination of steroid hormones in milk and blood of domestic animals have been used by veterinary surgeons in practice as a method of pregnancy diagnosis in cattle, horses and pigs. In goats, the complex metabolism of steroid hormones in the mammary gland has made the test unsatisfactory. In five non-pregnant Saanen does, milk and blood samples were taken daily through a complete oestrous cycle, and the concentrations of progesterone measured by ELISA. A wide variation in the pattern of progesterone concentration was recorded. In seven non-pregnant and early pregnant does (less than 35 days) the mean concentration of oestrogens in milk was 0.5 ng/ml. Pregnancy in 88 does was subsequently predicted, based upon a concentration of oestrone sulphate in milk over 0.5 mg/ml, and was approximately 80 per cent accurate for determination of both pregnancy and non-pregnancy when compared with actual kidding data. Reasons are given for these errors.