A 57-year-old man presented with atypical chest pain. Transthoracic echocardiography was performed and revealed a very large and well defined intra-myocardial multicystic mass in the posterolateral and basal inferoseptal segments of left ventricle suggestive of hydatid cyst. Although the echocardiographic diagnosis was straightforward, serologic test (hydatid cyst antibody) with enzyme-linked immunosorbent assay (ELISA) was performed which was positive for echinococcal infection. Other works up showed no involvement of other organ system. Albendazol was started for him and he referred to cardiac surgeon for resection of cystic mass.