Agenesis of the gallbladder and cystic duct is a rare congenital malformation. In 40-70% of cases this anomaly is associated with other gastrointestinal, skeletal, cardiovascular and genitourinary malformations. Lithiasis of the common bile duct is present in 25-50% of cases. In the majority of cases patients are asymptomatic or have symptoms compatible with a biliary disorder. A preoperative diagnosis is extremely difficult and the absence of the gallbladder is often an intraoperative finding. The authors report a case of isolated agenesis of the gallbladder. The relative embryology, development, diagnostic pitfalls, intraoperative behaviour and therapeutic strategies are discussed.