RÉSUMÉ
Hydatidosis is a zoonotic disease which is due to infectivity with larval stage of dog tapeworm,"Echinococcus granulosus". The disease is chronic and cysts can be lodged in different organs of the intermediate hosts. It has cosmopolitan distribution and impact health and economical challenges for the many countries throughout the world. In Iran, human cases are constantly reported from different medical centers, Therefore, accurate information on the distribution of the disease is first step for the control and prevention. In this descriptive study, demographic information [sex, age, occupation] about patients who underwent hydatid cyst surgeries during 2001-2004 in Tehran Milad Hospital were collected and analyzed. Among 78 patients who had hydatid cyst operations in Milad hospital, 56.5% were female and 43.5% male. Liver was the most commonly invovled organ. According to the result of this study, females were found more infected with hydatid cysts than males