Objective: Hydatid disease (HD), which is common in children in developing countries, causes many health problems. However no study has yet investigated the effect of HD on body composition. We thus compared results of bioelectrical impedance analysis (BIA) of healthy children and children with HD. Material and Method: BIA recordings were prospectively obtained from 30 children with HD and 29 healthy controls. We assessed body composition, basal metabolic rate, body mass index (BMI), phase angle, fat-free mass, body fat index (BFI), lean body mass (LBM), total body water (TBW), amount of extracellular water (ECW), capacitance, resistance, reactance, extracellular mass (ECM), and ECM:BCM ratio. Results: We found no significant between-group difference in mean age or gender (p>0.05). The phase angle, body capacitance, lean body mass, and extracellular mass were no significant difference between the groups (p>0.05). The extracellular water level was higher and BMI was lower in the patients than controls (p<0.005). Conclusion: HD impacted body structures, and BIA utility in children with HD deserves further investigation.