In order to investigate the superiority of local steroid injection over the intramuscular route, 37 patients with idiopathic carpal tunnel syndrome were treated with local or systemic steroid injections in a double-blind study. The first group received steroid injections into the carpal tunnel of the more severely affected hand and placebo into the deltoid muscle of the same side. The second group received steroid injections intramuscularly, and placebo into the carpal tunnel. The only significant improvement observed at the end of one month was in the steroid-injected hands of the first group. At 10-12 months follow-up only four (22%) of the 18 patients from this Group were symptom free.