To evaluate the success and degree of difficulty of inserting an epidural catheter into the caudal space in order to place its distal end at T10 in young patients.Forty-seven children up to 97 months old were studied. With the patients under general anesthesia with an orotracheal tube, a predetermined length of 18-G epidural catheter (Minipack: SYSTEM 2-Portex) was inserted to T10. X-rays were taken after surgery with 0.3 ml of iodine contrast. The catheter was considered well-placed if the distal end was between T10-T12; the approach was classified as easy, difficult or impossible.The catheter was placed at T12-T10 on 16 occasions: 6 in L1, 3 in L2, 4 in L3, 17 in L4-L5, and 1 in S1. T10-T12 was reached in 52% of patients under 1 year of age, but in only 17% of children older than 1 year. The L4-L5 epidural space was reached with 46 of 47 catheters. Advance was easy in 41 cases, with only 16 reaching the objective. Advance was difficult in 6 cases, with only 1 reaching L1 and none reaching T10-T12. All catheters were easily removed.It is not possible to guarantee the arrival of an 18-G epidural catheter to the thoracic epidural space by entering through the caudal route. In children over 1 year of age, the level of success decreases significantly. Easy advance of the catheter cannot be taken to be a sign of success.