In a few uncontrolled studies intravenous lidocaine has been used in the treatment of chronic pain. In a controlled study we used intravenous lidocaine in 18 patients with severe chronic pain states due to various but mainly neurological diseases. After the infusion of lidocaine 14 patients (78%) had significant pain relief ranging from 2 hours to 25 days. There was no significant effect of placebo infusion with isotonic saline. The mechanism of the pain relieving ability of intravenous lidocaine is unknown.