INTRODUCTION: Hydatid disease is a parasitic infestation caused by Echinococcus granulosus. The resulting large cysts in the lung are a special clinical entity called giant hydatid cysts. CASE PRESENTATION: An 18-year-old Yemeni woman presented with a dry cough and mild fever, with no history of chest pain, dyspnoea or weight loss. Chest X-ray revealed a homogenous opacity almost replacing the right lung. The patient underwent surgery which revealed a large, viable hydatid cyst measuring 26 x 18 x 5 cm. CONCLUSION: This case report provides evidence that non-complicated hydatid cysts, even if very large, have a good prognosis and can be safely treated by parenchyma-preserving surgery.