Clear cell tumour or "sugar tumour" of the lung is a rare primary neoplasm with unique histologic and electron microscopic features that may resemble those of metastatic renal cell carcinoma. An immunohistochemical studies are useful in a differential diagnosis these tumours: HMB45 in combination with a panel of various antibodies. The authors present a benign clear cell tumour of the lung, diagnosed on the base of its morphological, immunohistochemical and ultrastructural features.