OBJECTIVE Although studies have demonstrated increased frequency of gallbladder abnormalities among Downs syndrome (DS) patients in some countries, there is only one paper on this subject in the Brazilian literature. The aim of this study was to demonstrate the prevalence, clinical characteristics and evolution of lithiasis and biliary sludge among DS patients in a maternity and childrens hospital in Rio de Janeiro. METHODS This was a cross-sectional study followed by a retrospective cohort study on all individuals with an ultrasound diagnosis of gallbladder abnormalities. METHODS 547 DS patients (53.2% male, 46.8% female) attending the Instituto Fernandes Figueira in 2001 underwent abdominal ultrasound examination at ages of between one day and three years (mean: five months). Clinical and ultrasound data were analyzed. RESULTS In 50 patients (9.1%), the ultrasound demonstrated gallbladder abnormalities (6.9% lithiasis and 2.1% biliary sludge). Spontaneous resolution was observed in 66.7% of the patients with biliary sludge and 28.9% with lithiasis. Cholecystectomy was carried out on 26.3% of the patients with gallstones. CONCLUSIONS The results from this study and comparison with the literature suggest that DS patients are at risk of developing lithiasis and biliary sludge and should be monitored throughout the neonatal period, even if there are no known risk factors for gallstone formation. Most frequently, these gallbladder abnormalities occur without symptoms and spontaneously resolve in most non-symptomatic patients. DS patients should be monitored with serial abdominal ultrasound, and cholecystectomy is indicated for symptomatic cases or when cholecystitis is present.