Consolidations are characterized on CT by the presence of one or more airspace opacities with little or no volume loss. Because HRCT findings overlap among various entities, it may be sometimes to be impossible to make a definite diagnosis with imaging criteria alone. If the symptoms are chronic (weeks to months) the differential diagnosis may include alveolar proteinosis, bronchioloalveolar carcinoma, lymphoma as well as inflammatory diseases. This review describes the most common types of lung diseases associated with chronic appearance of consolidation and discuss the differential diagnosis.