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Background & aim: Hydatidosis is a zoonosis disease with worldwide distribution. This disease is caused by Echinococcus granulosus. Most cases of hydatid cyst of the liver and lung are reported, but rarely in the brain, heart, kidney, urethra, spleen, fallopian tubes, pancreas, and muscles are observed. The purpose of this report introduces a 9-year-old girl who was diagnosed with renal hydatid cyst. Case: This patient was a female, 9 years old of Kohgiluye and Boyerahmad Province, with feelings of right flank pain during urination. CT scan show a cystic lesion measuring 36 to 44 mm in the middle of right kidney. The patient's surgery was operated successfully And histopathologic examination confirmed the diagnosis of hydatid cyst. the patient was treated for four weeks with Albendazole (400 mg twice daily). Conclusion: The statistics show that the age of the infection with renal hydatid cyst is declining and this can makes many problems for the health of children and society. Each organ of the body can be attacked by Echinococcus granulosus, so in the presence of a space occupying lesion in the kidney, hydatidosis should be suspected. Calcified hydatid cyst in a such young child is a very rare condition