BACKGROUND: Hydatidosis is one of the zoonotic diseases which affect animals and human beings at the larval stage of Echinococcusgranulosus, thereby playing a role in exacerbating the economic and health problems in Iran. OBJECTIVES: This study was conducted to investigate the strains of Echinococcusgranulosus isolated from cattle hydatid cysts, in Khorramabad, in the Lorestan Province, west of Iran. METHODS: Twenty six isolates of hydatid cyst of cattle from lung (24 samples) and liver (2 sample) organs were collected from Golshan Slaughterhouse, in Khorramabad. All of the samples were transferred to the laboratory for morphometric characterization and molecular study. In morphological characterization, blade length of large (LBL) and small (SBL) hook and the ratio of blade length to total length in large (LBL/LTL) and small (SBL/STL) hooks and total length of large (LTL) and small (STL) hooks were measured. In molecular study, a partial sequence of cytochrome oxidase 1 (COX1) with 440 bp in length was amplified applying primers J3 and J4.5. Genomic DNA sequencing was performed by Sanger’s method. RESULTS: The morphological results showed that there is no significant difference between isolated from cattle hydatid cyst and sensu stricto strain (P<0.05). The results of molecular studies support the findings of morphological characterization. All sequences showed 100% identity with sensu stricto strain. CONCLUSIONS: The results from this study showed that sensu stricto strain (G1) is a causative agent of cattle hydatid cyst in Khorramabad. On the other hand, the cattle play a role in enabling the parasite to complete its cycle. Hence in order to execute a control program for minimizing the effects of this disease, the cattle shall be considered as a source of infection for dogs. The results of this study could be helpful in designing such control program in the region.