Improving animal production inevitably involves better management of reproduction. In this context, determining the physiological state of the animals by measuring hormones is an effective tool. A kit for radioimmunoassay of progesterone in goat serum has been developed specifically for determining the physiological state of goats in Morocco, and for early diagnosis of pregnancy (as early as 21 days after mating or artificial insemination). It is an innovative combination of polyclonal antibodies and radioactive tracers labeled with locally produced iodine-125. The kit has proved to be highly sensitive and specific. Its standard range covers the physiological rates observed during the goat's estrous cycle. Its sensitivity was estimated at 2.38 ng/ml and its detection limit at 0.01 ng/ml. This radioimmunoassay kit enables a large number of serum samples to be analyzed simply, rapidly, automatically and inexpensively.