Hydatid cyst disease is an important zoonotic infection commonly seen in various parts of the world. Humans are coincidental intermediate hosts in the lifecycle of the parasite Echinococcus granulosus (the cause of this disease), the definitive hosts of which are dogs and herbivorous animals. Turkey, primarily the Eastern and Southeastern Anatolian regions, is endemic for the disease. A 10-year-old male patient presented to our hospital with complaints of fever, cough and vomiting over the last week. The patient's chest X-ray revealed a typical water lily sign, and he was operated with the diagnosis of hydatid cyst. On post-operative day 20, piperacilin-sulbactam therapy was initiated, since cavity infection developed in the area from which the cyst had been removed. At the end of the 14-day medical treatment, a significant improvement was observed in the chest radiography. This case is presented to draw attention to the importance of monitoring patients closely for possible post-operative complications in pulmonary hydatid cyst disease.