Technical Abstract: Campylobacter causes human food-borne illness and epidemiological evidence indicates poultry and poultry products to be a significant source of human infection. Reducing Campylobacter in the poultry intestinal tract would reduce contamination of poultry products. Caprylic acid, a medium chain fatty acid, is effective in killing a variety of bacterial pathogens, including Campylobacter. However it has not been evaluated in the control of Campylobacter in preharvest poultry already colonized. The objective of this study was to evaluate the therapeutic effect of caprylic acid on Campylobacter colonization of the cecal content of 15 day old chicks. Three trials were conducted with six treatments/trial (n=10 birds/treatment). Treatments included: negative controls (no Campylobacter, no caprylic acid), positive controls (Campylobacter, no caprylic acid), 0.35%, 0.7%, 1.4% and 2.8% of caprylic acid supplemented in feed for the last 72 hours of each trial. On day 3 of age, chicks were orally challenged with five strains of Campylobacter jejuni. On day 15, ceca were collected and Campylobacter counts determined. Intestinal sections from each bird in Trial 3 were fixed and evaluated for enteric morphometric analysis. The supplementation of caprylic acid at 0.7% and 1.4% consistently reduced the colonization of C. jejuni in the chicken cecal content compared to positive control treatment. Body weight gain, feed conversion ratio and most of the enteric morphometric parameters did not differ between the caprylic acid and control groups. The results suggest that therapeutic supplementation of caprylic acid has efficacy in chicks and may provide a strategy for reducing Campylobacter in poultry.