Anatomic anomalies of the biliary tract are not uncommon, but gallbladder and cystic duct agenesis is rare, with an incidence of 0.01% to 0.04% and a frequency of 0.016% at autopsy. It is usually asymptomatic and discovered incidentally. Although this congenital anomaly is infrequent, it may be encountered in clinical practice; thus, the surgeon should be aware of the associated problems. A correct preoperative diagnosis of this congenital anomaly is difficult to establish because of the nonspecific nature of the symptoms and the relative inaccuracy of the currently available diagnostic tests. Here we report a patient with a preoperative false diagnosis of cholelithiasis that was found on laparoscopy and open surgery to be agenesis of the gallbladder.