Focal pulmonary ground-glass opacities (GGOs) can be associated with bronchioloalveolar carcinoma. The present retrospective study aimed to test the validity of a multistep approach to discriminate malignant from benign localised (focal) GGOs, identifies useful diagnostic features on computed tomography (CT), and suggests appropriate management guidelines. A stepwise approach, including oral antibiotics, follow-up high-resolution CT (HRCT) 40-60 days later and CT-guided core biopsy, was used. All cases with localised GGOs detected since 2001 were reviewed. CT features were described according to a structured scheme. In total, 40 patients were evaluated. Of these, 11 patients were diagnosed with benign GGOs, 19 patients had lung cancer and 10 were undetermined. Nonpolygonal shape, apparent radial growth and clear-cut margins were associated with a malignant histology. The specificity of CT findings was low. Diagnostic accuracy increased after oral antibiotics, follow-up HRCT and percutaneous core biopsy. Overall, 18 patients underwent surgery for lung cancer. In conclusion, malignant ground-glass opacities have a fairly typical appearance, but some benign lesions closely mimic their malignant counterparts. The stepwise approach adopted in the present study increased the diagnostic specificity and reduced time to definitive diagnosis. Segmentectomy might be the ideal resection volume for such tumours.