A case of lung angiodysplasia is reported here in. The diagnosis of this disease before surgery is difficult. The intraoperatory diagnosis of vascular disease was possible since the pulsating mass disappeared after the inflow and outflow blood vessels were selectively clamped. The abnormal placement of a venous vessel made the resection problematical. A careful anatomic and clinical study of the lesion, and the correct instrumental diagnostic approach may lead to a suitable therapeutic stategy, which respects both functional integrity and surgical radicality. The usefulness of a systematical selective clamping of the inflow and outflow blood vessels for an exact delimitation of the lesion emphasised.