An indirect ELISA has been developed successfully for the detection of defined amounts of goats’ milk (1–100%) in ewes’ milk. The assay uses polyclonal antibodies against goats’ whey proteins (GWP) raised in rabbits. The anti‐GWP antibodies were recovered from the crude antiserum by immunoadsorption and elution from a column containing immobilized GWP. The anti‐GWP antibodies were biotinylated and rendered goats’ milk‐specific by mixing them with lyophilized cows’ and ewes’ whey proteins. ExtrAvidin‐peroxidase was used to detect the specific anti‐GWP antibodies bound to goats’ milk proteins immobilized on 96‐well plates. Subsequent enzymic conversion of substrate resulted in discernible differences in optical density between mixtures of ewes’ milk containing variable amounts of goats’ milk.