The gallbladder is the site of various types of cysts that can mimic cystic neoplasms. Gallbladder cysts have been classified as congenital, acquired, and neoplastic cysts. Congenital cysts mainly include congenital simple epithelial cysts, ciliated foregut cyst, dermoid cysts, cystic choristomas derived from ectopic gastric mucosa, mesothelial cysts, duplication cysts, and bronchogenic cysts. Simple cysts may have a muscular wall but are not communicating with the gallbladder lumen. Acquired cysts are retention cysts, dilated Rokitansky-Aschoff sinuses, adenomyomatosis, cystic changes of fistulas, cystic abscesses, inflammatory pseudocysts, and parasitic cysts. Retention cysts are caused by obstructive gallbladder changes induced by stones, tumors, or sludge.