Campylobacter spp. are now estimated to be the leading bacterial cause of human foodborne illness in the United States, causing more than a million human illnesses at a cost exceeding $1 billion dollars annually. Swine carry high numbers of Campylobacter coli and occasionally can carry high numbers of the more pathogenic strain, Campylobacter jejuni. This project was conducted to further research and development of a potential anti-Campylobacter intervention showing promise to reduce these foodborne pathogens in pigs. Our laboratory studies confirmed that two compounds, diphenyliodonium chloride and thymol, each exhibit significant and persistent Campylobacter-killing activity when administered to mixed populations of swine fecal bacteria at doses as low as 0.01 and 1.0 mM, respectively. Results from two pig feeding studies revealed that neither compound adversely affected dry matter intake or live weight gain when fed for 7 days in diets supplemented with less than or equal to 0.00042% diphenyliodonium chloride or 0.0201% thymol (wt/wt). However, these treatments were ineffective in reducing Campylobacter in the lower gut most likely due to their absorption or degration in the stomach or small intestine. These results indicate that while these compounds effectively kill Campylobacter, encapsulation or other protective technologies will ultimately need to be developed to deliver effective concentrations of these compounds to the lower gut to enhance their efficacy against Campylobacter in growing swine. Future studies are planned to test such products in swine.