Hydatidosis or echinococcosis a common parasitic infestation caused by Echinococcus spp. Dog is the principle reservoir of adult worm. Hydatid cyst is commonly found in liver and lungs.Slaughters, tanners, shepherds, butchers and veterinarians and those coming in close contact with the animals are at a high risk of contracting this disease. Herein, we present case of a 16-year-old young male who had large hydatid cyst in the lung, double the size of his heart and this giant cyst occupied almost entire hemithorax.It obliterated the right heart border and the costophrenic angle mimicking a large pleural effusion.The lateral view and CT Thorax revealed the giant Hydatid cyst. The patient underwent surgical intervention, received albendazole and discharged uneventfully.