The aims of this study were to present and discuss ultrasound findings of prenatal fetal cholelithiasis in two cases with different etiology and evolution. Case 1: a pregnant woman from sub-Saharan Africa, suffering from Lyme disease, was treated with ceftriaxone sodium. Six weeks later, biliary sludge associated with polyhydramnios was detected in the fetus and the fetal growth percentile was 14. Emergency caesarean was performed at 36 weeks of gestation due to fetal distress. Biliary sludge persists in the two-and-a-half-year-old child. Case 2: the fetus of a Caucasian woman with normal pregnancy showed multiple cholelithiasis associated with polyhydramnios at 31 weeks of gestation. At 39 weeks and 4 days, cesarean section was performed due to lack of dilation. The biliary disease resolved spontaneously at seven months of age, with no associated abnormalities. In conclusion, prenatal diagnosis of cholelithiasis is straightforward, but prognosis cannot be defined yet. Serious complications do not arise in 70% of cases, but severe diseases may ensue in 20%. Persistence of cholelithiasis after one year of age results in cholelithiasis in childhood and beyond. Biliary sludge is associated with worse prognosis than cholelithiasis when it appears before 28 weeks of gestation.