Eighty-eight rabbits weaned at the age of 35 days were divided into four groups. Rabbits of the first two groups were fed a granulated feed, free of antimicrobials. Rabbits of the 3rd and the 4th groups were fed the same diet, supplemented with caprylic acid at 5 g/kg, and with triacylglycerols (TAG) of caprylic and capric acid at 10 g/kg, respectively. Rabbits of the 2nd, 3rd and 4th groups were challenged orally with 10(9) cells of Escherichia coli of the O103 serogroup. Numbers of coliform bacteria in faeces of non-infected rabbits averaged 4.66 log(10)cfu/g. Six days after inoculation, caprylic acid and TAG of caprylic and capric acid decreased faecal output of coliforms from 10.18+/-0.62 to 7.79+/-0.48 log(10)cfu/g and 8.04+/-0.50 log(10)cfu/g, respectively. In the 2nd, 3rd and 4th groups 15, 11 and 9 infected rabbits died, respectively. However, the differences in mortality rate were not statistically significant. Surviving rabbits were slaughtered at 53 days of age. In caecal contents of infected rabbits, numbers of coliform bacteria were significantly reduced from 8.71 log(10)cfu/g to 5.55-5.83 log(10)cfu/g in treated groups. It can be concluded that both antimicrobial lipids are active against coliform bacteria, and may improve the resistance of weaned rabbits to enterocolitis.