Hydatid cyst is a parasite disease, which is common in those countries where animal husbandry is extensive, but preventive medicine is lacking. Endemic regions are South Europe, South America, Africa, Turkey, Australia, New Zealand, and India. In the study, a sudden death case due to cardiac hydatid cyst rupture located in right ventricle has been presented with a review of the literature. The victim was a 10-year-old girl of a family who raised sheep. External examination of the body showed congestion in both the head and face but neither trauma nor evidence of violence or eruptions on the skin were found. At autopsy, through a vertical incision on the frontal surface of truncus pulmonalis, a total of 8 daughter cysts were obtained. A 6 × 5 cm cyst was observed in the right ventricular apex. In those countries where hydatid cyst is endemic, and when sudden unexpected death occurs in individuals involved in animal husbandry, cardiac hydatid cyst must be kept in mind as a cause. © 2008 by Lippincott Williams & Wilkins.