Echinococcosis is very frequent helminthic infection in human being. The disease is endemic in Iran and particularly in its northwestern region, East Azerbaijan. The objective of this study was to study demographics of patients with cystic echinococcosis in East Azerbaijan; as well as to repot the sites of involvements. In this cross-sectional study, 318 patients with surgical and nonsurgical cystic echinococcosis were recruited from three referral centers in Tabriz within a 10-year period of time. The patients demographics (age and gender) and the site of infection were investigated. Among the patients, females were predominant (57.5 vs. 42.5%). The mean age of patients was 32.59±18.47 (range: <1-87) years and the most frequently age group was 20-30 years (23.6%), followed by the age groups of 30-40 years (21.7%), 10-20 years (14.2%), 40-50 years (11.9%), 50-60 years (11.3%), <1 year (6%), 60-70 years (4.7%), 1-10 years (4.1%) and finally, >70 years (2.5%). The lung was the most frequently infected organ (48.1%), followed by the liver (28.9%), gallbladder (3.5%), spleen and kidney (each one in 2.2%), abdomen, intestine, pleura, bronchus and mediastinum (each one in 1.6%), chest wall and heart (each one in 1.3%), brain, pericardium, facial sinus, pancreas and esophagus (each one in 0.6%) and the ovary, uterus, axillary region, pelvis and femur (each one in 0.3%). In conclusion, this study showed that the patients with hydatid cysts in East Azerbaijan Province are mainly females in the age group of 20-40 years. The lung and liver are the major sites of infection in these patients.