A survey of surgically treated cases of hydatidosis in the province of Valdivia, Chile, was done. Data were provided by the Regional Hospital of Valdivia, and a period of eleven years was covered (1976-1986). Disease, treatment and related data from each patient were consigned. For the analysis, the information was grouped according to: sex, age, cyst location, condition of the cyst, concomitance with another pathology, condition at time of discharge, hospitalization period and number of repeat hospitalizations. In the period studied, 197 cases of hydatidosis were surgically treated. The sex distribution was 53.3% for males and 46.7 for females; the age group 10-19 years was the most affected by the disease (19.3%). The most frequent locations of hydatid cysts were the liver (58.9%) and lungs (36.5%); the 38.6% of the patients showed complicated cysts, mainly with bacterial infections (11.7%); also, 20% of the cases presented a concomitant liver-related pathology. After the operation, 153 (77.7%) clinically recovered and 27 (13.7%) non-recovered patients left the hospital and 7 (3.5%) cases died while hospitalized. The average hospitalization period was 29 days. During 1976-1986, 24 patients were rehospitalized.