March, 1991, to June, 1992, five lung transplantations for end-stage lung disease were successfully performed at the Ospedale Maggiore Policlinico in Milan. All patients underwent high-resolution CT (HRCT) of the lung in a complex follow-up program to identify specific abnormalities of acute and chronic rejection (bronchiolitis obliterans) and to monitor the resolution of the bronchial anastomosis. Twenty-two HRCT exams were performed. In patients with acute rejection HRCT failed to identify specific abnormalities of lung parenchyma. In contrast, in one patient with pathological evidence of early bronchiolitis obliterans HRCT showed decreased peripheral vascularization. In the study of the bronchial anastomosis, HRCT showed optimal anastomosis resolution in 4 patients, whereas in one patient with a granuloma demonstrated by fibrobronchoscopy it confirmed the lesion showing also a small pneumomediastinum. Even though the HRCT finding of decreased peripheral vascularization does not appear to be specific for bronchiolitis obliterans, it may be of value in suggesting the diagnosis of early bronchiolitis obliterans in lung transplant. HRCT should be used in all patients with bronchoscopic diagnosis of bronchial complication to study the lesion and its mediastinal spread.