In developing countries,Campylobacter jejunicauses diarrhea and dysentery, especially in children less than one year of age. Breast feeding protects against infectious diarrhea, with milk IgA antibody playing a determining role. Therefore, it has been proposed to increase the protective effect of human milk by vaccinating women of child‐bearing age. To identify antigens which may induce protective breast‐milk IgA, we analyzed 60 strains ofC. jejuniisolated from asymptomatically‐ and symptomati‐cally‐infected breast‐fed children less than 12 months of age. Surface antigens ofc. jejuni, separated by polyacrylamide gel electrophoresis, were probed with breast milk collected concurrently with the fecal sample from whichC. jejuniwas isolated, and specific IgA was developed by immunoblotting. Our results indicate that milk antibodies against three high molecular weight bacterial surface antigens of 95, 110 and 185 kDa are involved in protection of infants infected withC. jejuni (p =0.00964 for one‐tailed Fisher'