Background: Small intestine alterations produced by the enterotoxigenic capacity of Campylobacter jejuni subsp. jejuni are similar to the hydric, electrolytic and pathological changes caused by choleraic and thermolabile Escherichia coli toxins. Aim: To study the enterotoxigenic capacity of 4 strains of Campylobacter jejuni subsp. jejuni using the intestinal loop model. Material and methods: Rat intestinal loops were inoculated with culture filtrates of the four strains. Enterotoxigenicity was assessed by fluid accumulation, the increase in Na+ and Cl- in the loop fluid, and cAMP increases in loop tissues. An enterotoxigenic Escherichia coli strain and sterile Brucella both were used as positive and negative controls, respectively. Results: The filtrates of two strains produced fluid accumulation in the loops, significantly increased Na+ and Cl- secretion to the intestinal lumen and increased tissue cAMP levels. Conclusions: Some strains of Campylobacter jejuni subsp. jejuni are able to show enterotoxigenicity in vivo, increasing cAMP levels in the intestinal cells and altering electrolyte exchange mechanisms.