With the view points of size, shape and arrangement pattern, authors present normal mediastinal lymph node from the analysis of 61 cases of CT scan and umltidirectional section of 2 cadavers. The results were as follows: 1. Transverse diameter of the lymph nodes, demonstrated in cadaver section, was 3 to 6mm in upper paratracheal area and 5 to 14mm in juxta-carinal and AP-window area. Arrangement of the lymph nodes showed tendencly of longitudinal direction in lower paratracheal, and juxtacarinal area, while that of AP window showed tendency of AP difection as long axis. 2. Mean and the largest size of the lymph nodes demonstrated in CT scan were 3.7mm, 8mm in upper paratracheal area, and 6mm, 12mm in lower paratracheal area, and 7.1mm, 14mm in juxtacarinal area, and 6.3mm and 11mm in aorticopulmonary window area. 3. Size of the lymph nodes in CT scan showed linear increasing tendency according to increasing age(y=0.32, p<0.005). 4. Shape of the lymph nodes in CT scan were mos ly round in upper paratracheal area while that of aorticopulmonary window showed higher incidence of oval and elongated shape. 5. Recommended size criterior of abnomal lymph node is 10mm in upper paratracheal area and 15mm in the other area.