BACKGROUND: The spread of local anesthetics in the epidural space varies significantly between patients. Studies have demonstrated radom cephalad or caudad migration of the epidural catheter. However the relationship between catheter direction and epidural spread of local anesthetic has not been well documented. METHODS: A single-orifice epidural catheter with an end hole was inserted caudad at L2-3(caudad group) or cephalad at L3-4 intervertebral space(cephalad group) in 38 patients. The epidural catheter was filled with 1 ml of Omnipaque dye, and fluoroscopic determination of the exact position of the epidural catheter tip was done to locate the catheter tip within the range of the third lumbar vertebral body. After test dose of 3 ml, 2% lidocaine 22 ml with epinephrine 1:200,000 was administerd at a rate of 0.5 ml/s in supine position. RESULTS: Age varied from 20 to 36 years(mean age, 24.2 3.9 years). There was no significant difference in the rate of spread of skin analgesia, the upper analgeseic level and the degree of the motor block between the two groups. Although the time to reach maximum motor blockade(33.8 11.0 min in the cephalad group, 27.4 11.4 min in the caudad group) and skin analgesia to S 5 segment(21.3 7.6 min in the cephalad group, 17.1 5.4 min in the caudad group) was slightly shorter in the caudad group, the differences were not statistically significant. CONCLUSIONS: This study indicates that the spread of skin analgesia is not affected by the epidural catheter tip direction when lidocaine is injected into the epidural space in young adult patients.