Gallbladder agenesis (GA) is a rare embryological anomaly that presents acute cholecystitis like-symptoms. It is often an incidental finding diagnosed during surgery. We reported a case of GA in a patient who presented with dyspepsia and acute right upper abdomen pain with ultrasonographic signs of acute lithiasic cholecystitis. The preoperative assessment, according to first-level exams, is oriented to the diagnosis of acute lithiasic cholecystitis with atrophy and sclerosis. During laparoscopy, the proximal transverse colon was found strictly adherent to gallbladder fossa. The gallbladder was found to be absent. The surgical procedure consisted of lysis of multiple colo-hepatic adhesions. The diagnosis of congenital GA was made laparoscopically. The postoperative radiological images, based on CT and MR examinations, documented the diagnosis of GA with a biliary duct anatomical variant. The recovery was uneventful and the patient remained symptom-free for more than four years. GA is a clinical challenge that still poses diagnostic and therapeutic dilemmas. Although no diagnostic and therapeutic algorithm is accepted worldwide, due to heterogeneity of clinical scenarios and the variability in hospital facilities, surgeons have to be familiar with this rare entity, and conversion in laparotomy or unnecessary operative procedures should be avoided in the same operative setting.