An enzyme‐linked immunosorbent assay (ELISA) for the detection of porcine pepsin in milk‐clotting enzyme preparations has been developed. The assay is capable of detecting porcine pepsin in the range 1μgto 1 mg ml‐1without enhancement or modification. The specificity of the technique was studied by inhibition assay. Slight cross‐reactions with bovine rennet andMucor mieheirennet occurred at high concentrations (1.0 mg ml‐1). The ELISA used in this investigation appears to provide a quick, sensitive and specific method for the detection of porcine pepsin and has potential applications in the dairy industry.