Salmonella is an important cause of severe bacterial enterocolitis in children. Results of traditional diagnostic culture methods take at least 24 to 72 hours. Due to the easy availability and noninvasiveness of ultrasonography, we investigated whether or not imaging studies could provide faster results. From November 1, 2000 to October 25, 2001, we collected 48 continuous patients with Salmonella enterocolitis as the study group and 52 continuous patients with rotavirus gastroenteritis as the control group. We measured the thickness of the right lower quadrant colonic wall and sought to learn whether or not there were ascites behind the bladder and/or in Douglas's pouch. Thickness of the colonic wall greater than 5 mm was defined as abnormal. The mean thickness of the colonic wall of the study group was greater than that of the control group (p < 0.01). A total of 41 patients in the study group had colonic wall thickening, but only one patient in the rotavirus control group had thickening (p < 0.01). The mean C-reactive protein, white blood cell (WBC) count and percentage of neutrophils in the WBC differential classification were statistically different between the study and control groups (p < 0.01, p = 0.04, p = 0.02, respectively). A total of 41 patients in the study group had occult blood (≥±) in their stool; 17 patients in the control group had stool occult blood (p < 0.01). We emphasize that, although ultrasonography did not enable us to make a definitive diagnosis of Salmonella enterocolitis, it could be used to identify the pathologic changes in the bowel and intraabdominal lesions, and to grade the degree of enterocolitic invasion.