Abstract: Objective: To investigate the value of CT image findings in differentiating diagnosis of bronchioloalveolar carcinoma(BAC) and pneumonia.Methods: Twenty-six patients of bronchioloalveolar carcinoma and thirty-six patients of pneumonia underwent chest scans with Siemens 16-slice CT.Image findings of consolidation,pseudocavitation,air bronchogram sign,leafless tree sign,crazy paving,ground-glass opacities,consolidation crossing lobe,bulging of fissure,atelectasis,CT angiogram sign,coexist nodule,lymph node,pleural effusion,pleural thickening were analysed.Results: Statistically significant(p<0.01) findings that were more often seen on CT scans of patients with consolidative BAC than on those of patients with pneumonia included low density of consolidation,pseudocavitation,leafless tree sign,crazy paving,ground-glass opacities,consolidation crossing lobe,bulging of fissure,CT angiogram sign,coexist nodule.Conclusion: CT may be helpful in differentiating consolidative BAC from pneumonia if image findings of low-density consolidation with pseudocavitation,leafless tree sign,crazy paving,ground-glass opacities,consolidation crossing lobe,bulging of fissure,CT angiogram sign,coexist nodule is shown on CT.