This study is aimed at elucidating with in vitro experiments the time course of alteration of ileal motility caused by in vivo exposure of ligated loops of ileum to toxin A (1 microg/ligated loop) of Clostridium difficile. In the sham-operated animals no significant alteration of motility was observed. In ligated loops directly injected with toxin A and in loops neighboring those administered with this toxin, a biphasic time course of motility alterations was observed. There was initially (2 h after toxin administration) an increase in spontaneous motility and in the amplitude of maximal contraction induced by potassium and acetylcholine. Afterwards there was a progressive depression of motility, which was more severe in loops directly injected. These results suggested a significant progressive depression of rabbit ileal motility induced by toxin A from C. difficile.