The lower epidural space and sacral hiatus were studied by positive contrast radiogrphy, injection of 20cc of 60% Urografin and 25cc of 1.5% Lidocain through sacral hiatus in 20 Korean adults. The radioanatomic characteristics of the lower epidural hiatus obtained from this study were as follows: 1. The mean length of the sacral canal from the upper of the first segment of sacrum to the apex of the sacral hiatus was 9.8$pm$2.9cm. 2. The apex of sacral hiatus was located most ofenly at the 4th cacral vertebra in 10 cases (50%), and the highest one was located at the upper one third of the second sacral vertebra (10%). 3. The mean intercornual distance was 2.2$pm$0.4cm. The mean distance from the apex of the sacral hiatus was 3.1$pm$1.5cm. The mean A-P diameter of the sacral canal was 0.8$pm$0.2cm at the lowest location was noted at the middle one third of third sacral vertebra. 5. There was a relatively symmetrical distribution of the dye leaked out alongside the nerve roots. The onges leak-out was recognized at S-1 and in the order of length it was able to be arranged as S2, S3 and L1. 6. The upper border of Urografin in the epidural space was commonly located below the level of the first lumbar vertebra (70%) and the mean length was 30$pm$8.5cm. In majority of cases the anesthetic level was determined at the level of L-5 to S2.