The authors classify rupture of echinococcal cysts into three types: contained, communicating, and direct. Contained rupture occurs when only the parasitic endocyst ruptures and the cyst contents are confined within the host-derived pericyst. When cyst contents escape via biliary or bronchial radicles that are incorporated in the pericyst, the rupture is communicating. Direct rupture occurs when both the endocyst and the pericyst tear, spilling cyst contents directly into the peritoneal or pleural cavities or occasionally into other structures. Communicating and direct forms have more serious clinical implications than contained rupture, but even contained rupture should have prompt surgical attention to prevent it from developing into one of the other forms. Untreated communicating rupture of a liver cyst can lead to obstruction of the biliary system with a 50% mortality rate. Direct rupture may cause anaphylaxis, and it should be managed surgically, possibly with adjunctive treatment with antihelminthic drugs to decrease the possibility of metastatic hydatosis.