The objectives of this two-part study were: (1) to determine whether strains of Arcobacter butzleri independently cause enteritis, and (2) to investigate the enteropathogenicity of Arcobacter butzleri. For Part I, six well characterized A. butzleri isolates were tested using the gut loop assay in rabbits and pigs. Fluid secreted in loops was measured and cultured for A. butzleri. In addition, intestinal segments, liver, and splenic tissues were collected, cultured, and examined for histopathology. Of the 60 experimental rabbit loops tested, 13% (8/60) produced fluid. Of those fluid-containing loops, 88% (7/8) had been injected with strain 4056. In young pigs, all experimental strains produced fluid amounts significantly different from the positive enteropathogenic E. coli control (P<0.05). Only strain 4056 caused fluid accumulation significantly different from the negative PBS control (P<0.03). There was no significant difference in mean fluid accumulation when experimental strains were compared (P>0.05). The major histological change, seen in rabbit and pig loops with fluid secretions, was an infiltration of leukocytes in the gut wall. In Part II, strain 4056, the most responsive strain from the first part of the study, was tested in the pig ileal loop assay. No fluid accumulation or pathologic changes were observed in intestinal tissues. Restriction enzyme analysis showed two different band patterns for A. butzleri present in tissues. It was concluded that A. butzleri, depending on the strain virulence and host susceptibility, can cause mild enteritis with watery diarrhea. / Master of Science