We recently compared the analgesic effects of the two presentations of levobupivacaine available on the French market, (0.625 and 1.25 mg.mL-1 in pre-filled bags), both with sufentanil. It appeared that the high concentration was more powerful, however leading in some cases to give doses of levobupivacaine superior to the label's recommendations. This indicates to use the low concentration, with a risk of a poorer efficacy. Our aim is to show that efficacy can be restored with a systematic addition of clonidine, which has documented analgesic properties when administered perispinally.