High Resolution computed Tomography(HRCT) was done in 22 cases of disseminated small nodular shadow from plain chest X-xay, which was included in metastatic lesion, Miliary tuberculosis, pneumoconiosis etc. and following results were obtained. Most of metastatic nodule (n=8) showed more than 1.5mm in diameter and the margin of nodule was discreten(n=8) and many cases(n=8) were associated with thickened bronchovascular sheath or interlobular septum and hilar and mediastinal lymphnode enlargement(n=6). One case turned out to be not true nodule in HRCT but revealed thickened interlobular septum and bronchovascular bundles. All cases of miliary tuberculosis(n=8) showed even sized, well marginate and less than 3mm in diameter of nodule without evidence of thickening of bronchovascular bundle or interlobular septum. Each cases of pneumoconiosis, histiocytosis X, diffuse panbronchiolitis(DPB) showed ill defined nodule and associate finding of DPB was peripheral bronchioloectasis. HRC is useful method to exact evaluation of nodular lesion and find out associated findings for differential diagnosis of disseminate small nodular shadow in plain chest X-ray.