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Abstract Background and objectives: Hydatid cyst is one of the most important zoonotic parasitic diseases produced by means of Larva stage of Echinococcus granulosus. Since this Hydatid cyst is a widespread disease in many regions of the world and Iran, we decided to study the epidemiological situation of patients infected with hydatid cyst who were operated in hospitals of Qom, Iran (2004-2007). Material and Methods: In this Cross-sectional retrospective study, we surveyed the Medical records of 19 patients infected with hydatid cyst, who were operated in hospitals of Qom (2004-2007). Patients’ demographic data including gender, age, career, dwelling place, number of cysts and the infected organ were collected and analyzed by SPSS software. Results: of the 19 patients, 12 cases (63.2%) are female and seven cases (36.8%) male. The highest rate of infection is related to 21-30 year group (31.65%) homemakers (52.7%) and urban (89.5%). The results show that the organs involved are liver (73.7%) and lung (26.3%). All patients infected with pulmonary hydatid cyst are male. Conclusion: Since 63.2 percent of infected people are female and homemaker, having contact with vegetables contaminated with parasite ova is the most important way of infection transmission. Key words: Hydatid cyst, Epidemiology, Surgery, Iran