Imaging, particularly high-resolution CT (HRCT), plays an important role in the assessment of patients with interstitial lung disease. HRCT consists of thin sections (around 1 mm) and image reconstruction with a sharp edge enhancing algorithm to optimize spatial resolution. It depicts the pattern, extent, and distribution of disease and thus provides important clues to the diagnosis. It is also helpful in selecting the optimal biopsy site and determining whether the findings on the biopsy specimen are representative of the overall process. Interstitial lung disease may result in six distinct patterns on HRCT: interlobular septal thickening, reticulation, cystic pattern, nodular pattern, ground-glass opacities, and consolidation. The differential diagnosis is based on the predominant pattern or combination of patterns, distribution of findings, and clinical information.