Progesterone concentration in the milk of goats measured by an enzyme-immunoassay using horseradish peroxidase as tracer is described. This method for early identification of non-pregnant and pregnant goats is applicable to farms situations, the assay has very high sensitivity and comparison with radio immunoassay based on tritiated tracer showed good correlation (r=0.78). A diagnostic level of 10 ng progesterone per ml of milk was determined in order to distinguish between pregnancy and non-pregnancy when the sampling of the milk is done in the period between 20 and 23 days after service.