Objectives: This is a protocol for a Cochrane Review (intervention). The objectives are as follows:. To assess the effects of corticosteroids injected in or around the carpal tunnel for the treatment of carpal tunnel syndrome (CTS), compared with placebo, no intervention, or other surgical or non-surgical interventions. In more detail, we will seek evidence to answer the following specific questions. Is local corticosteroid injection superior to no treatment, a placebo or sham injection? Is local corticosteroid injection superior to any type of surgery? Is local corticosteroid injection superior to other commonly used non-surgical measures: splinting, oral non-steroidal anti-inflammatory drugs (NSAIDs), oral steroid, nerve gliding exercises, low-level laser or therapeutic ultrasound? What is the most effective type of steroid, dose, and number and method of injections when administering local corticosteroid injection? Is local corticosteroid injection superior to other less commonly used or novel non-surgical measures?.