Colovesical fistulas represent a possible less frequent complication of diverticular disease of colon. They represent a complex condition because of the possible and unexpected evolution into a septic shock with a high risk of death. The Authors report three cases of colovesical fistula as a complication of diverticular disease. They underline the importance of early diagnosis, specific antibiotic therapy and appropriate surgical therapy realized in one or two stages according to general and local conditions of each patient.