BACKGROUND: Carpal tunnel syndrome (CTS) is a commonly seen peripheral nerve mononeuropathy. Corticosteroid injection within the carpal tunnel is among the conservative treatment options. The exact mechanism of action of steroids is not fully clear; decreased inflammation surrounding nerves or tendons is thought to be the main effect. Lidocaine has been shown to have anti-inflammatory effects on certain cells (monocytes, macrophages, neutrophils etc.). The aim of this study is to evaulate the efficacy of lidocaine treatment as a alternative to corticosteroid treatment in carpal tunnel syndrome.