Background: This study was designed to determine the frequency of hydatidosis in Khuzestan Province, Iran and to evaluate the antibody changes in infected individuals after treatment Methods: Overall, 454 sera were collected from health centers of Khuzestan Province, southern Iran (from 2013 to 2018). Demographic data such as age, gender and history of disease were recorded. Serum samples were investigated for antibody against CE by ELISA using antigen B. Thirty six of cases were followed up after treatment. Results: Among the 454 evaluated cases, antibody against CE was detected in 184 (40.52%) including 115 (62.5%) females and 69 (37.5%) males. Age distribution was from 8-97 yr, the highest prevalence of hydatid cyst was observed in age group 40-49 years. Liver was the most infected organ (76.63%). Relapse of CE occurred in 23 of patients. In the majority of patients the antibody decreased, whereas in some cases increased CE antibody observed during post-treatment follow up. Conclusion: Current study indicated the high prevalence of hydatidosis and rate of relapse after treatment among suspected patients. Therefore, long periods and regular follow-up of patients after treatment is necessary and for these monitoring, antibody assay can be an appropriate method.