The segmental spread of epidural analgesia was measured in seventeen surgical patients aged between 17 and 52 years, and in fourteen patients between 60 and 77 years. The upper level in the young was 6.29(±1.56) thoracic vertebra level, but in the elderly was 4 (±0.65_ thoracic vertebra level at 20 minutes after epidural injection of 1.5% lidocaine 20 ml. A given volume of solution spreads to 0.9, 1.07, 1.54, 2.29 segments greater upper extent at 5, 10, 15, 20 minutes after epidural injection and 0.57, 1.07 segments greater lower extent at 5, 10 minutes in the elder than young. So with increasing age relatively small amounts of solution are required, to produce the same extent of anesthesia in the young.