Unhealthy nutritional habits and the current western lifestyle have led to an increased incidence of acute diverticulitis, which mainly affects older patients. However, the disease course in younger patients might be more severe. It has a continued increase in surgical practice, as it is the most common clinical condition encountered in the emergencies. Diagnosis and management have changed over the past decade. C-reactive protein > 170 mg/L represents the cut-off point between moderate and severe diverticulitis, and a CT scan is mandatory. It demands urgent surgical management and has high morbidity and mortality rate, especially in immunosuppressed patients, reaching up to 25%. According to the contemporary guidelines, there have been certain indications for conservative management and re-evaluation (administration of antibiotics, CT-guided drainage of the abscess, when it is > 4 cm). They include pericolic air bubbles or a small amount of fluid, absence of abscess within a distance of 5 cm from the affected bowel or abscess ≤4 cm. In other cases, Hartmann's sigmoidectomy is the procedure of choice. An alternative choice, nowadays, is resection and primary anastomosis with or without diverting stoma, especially in younger patients. Laparoscopic lavage only versus primary resection has been performed in severe cases of Hinchey III or IV. Damage control surgery, possible open abdomen, and reoperation are recommended in severe sepsis. Hinchey's classification may not be absolutely adequate, and several modifications have been proposed. Current classification criteria (CRP, qSOFA score) are more appropriate. The decision-making must be individualized depending on the hemodynamic status (septic shock), age, comorbidity, immune status, intraoperative findings, and MPI (Mannheim peritonitis index).