The effect of caprylic acid (CA) on Campylobacter jejuni in chickens was evaluated using two approaches: dietary supplementation or surface treatment of chilled chicken carcasses. To analyze the dietary effect of CA, individually housed broiler chickens (n = 48) were artificially infected with C. jejuni VFU612 (10(6) colony-forming units [CFU]/bird) on the 21st and 35th days of life. Dietary CA (2.5 and 5 g/kg of feed, fed throughout the entire experiment) significantly decreased C. jejuni shedding (p<0.05). However, the effect only lasted for 3-7 days after infection. The numbers of Campylobacter shed by the positive control birds reached its maximum on the 37th day of life, while on that same day, both Treatment I and Treatment II groups shed significantly lower (p<0.05) numbers of Campylobacter (by 0.8 and 1.8 log10 CFU/g, respectively). Also, peak shedding was delayed by 1 day in both treated groups. After euthanasia of each chicken on the 42nd day of life, no differences in Campylobacter counts in the crop, gizzard, ileum, and cecum were found between the positive control and the treated groups (p>0.05). Surface contamination of the chilled chicken halves was performed with C. jejuni VFU612 (clinical isolate) and CCM6214 (collection strain). Surface treatment with CA at 1.25 and 2.5 mg/mL for 1 min significantly reduced C. jejuni VFU612 contamination of chicken skin (p<0.05) by 0.29-0.53 and 1.14-1.58 log10 CFU/g of skin, respectively. Counts of C. jejuni CCM6214 were reduced by 0.68-1.65 log10 CFU/g of skin). In conclusion, dietary CA affected numbers of C. jejuni in the gastrointestinal contents of chickens, whereas surface treatment reduced C. jejuni contamination in processed chicken carcasses.