Between July, 1992 and June, 1994, 151 pediatric patients who had ceftriaxone therapy for probable or definite bacterial enteritis were prospectively evaluated by serial abdominal ultrasonography. All patients received a dose of > or = 50 mg/kg/day and for a duration of 3 or more days. Five patients developed gallbladder precipitates or pseudolithiasis during treatment. Fasting and patients older than 24 months were probably the significant risk factors associated with this phenomenon (p < 0.05). However, no significant differences in sex, dose (50 vs. > 50 mg/kg/day) or duration of therapy (< 5 vs. > 5 day) were observed between patients who received ceftriaxone with and without the development of this gallbladder abnormality.