Thirteen children between the ages of six months and six years with acute diarrheal syndrome were investigated for Small Bowel Transit Time (SBTT). The results were compared with another study made by our section in which eleven children were studied; seven with chronic non-specific diarrhea and four controls. All the subjects had a double lumen catheter positioned in the small intestine with ports located 1 meter apart. A bolus of 4% P.E.G. was delivered into the stomach and the rate of appearance was monitored at the two collecting ports. Four normal children had a small bowel transit time of 60 min/m; one subject with shigella revealed a small bowel transit time of 30 min. Eight children with acute non-specific diarrhea had a mean of 90. Seven with chronic non-specific diarrhea had a mean of 99 min/m. Four patients with serotype positive E. coli had a mean of 83. In each case where SBTT was delayed there was also an increase in luminal free bile acids. In conclusion, diarrheal syndrome in children may present accelerated or delayed SBTT according to the etiology of each. Children with diarrheal syndrome showed an abnormal bile acid pattern in the duodenum which may represent a bacterial overgrowth and introduce a pathogenic role in the disease.