Cholecystitis is the most prevalent surgical condition affecting populations in industrialized countries. Rather than a single clinical entity, cholecystitis is a class of related disease states with different causes, degrees of severity, clinical courses, and management strategies. Appropriate care of the patient who has a diseased gallbladder requires a broad understanding of the acute, chronic, and acalculous cholecystitis syndromes, and awareness of their particular clinical nuances and potential complications.