Background: Intravenous ceftriaxone therapy in adults can cause microlithiasis and acute cholecystitis. Conservative treatment has been the ordinary choice for dealing with such situation, most of the times because of benign evolution observed in children. Presentation of case: The authors present a case report of acute cholecystitis with microlithiasis in a 56–year–old male following ceftriaxone therapy, that requires a surgical management. Discussion: Adults receiving ceftriaxone therapy must have a closely follow–up considering, the potential risk of surgical complications, mainly the acute cholecystitis. Conclusion: Acute abdomen after intravenous ceftriaxone treatment has been usually underestimated and surgeons must be aware about such complication in adult population.