We studied steroid irrigation of the median nerve during surgical decompression in carpal tunnel syndrome through a prospective randomized controlled study. After sample size calculation, 20 patients were randomized into two groups: one group had a release of the transverse carpal ligament alone, and the other one had a release associated with steroid irrigation of the median nerve. The patients were evaluated preoperatively and postoperatively at 15 days and 2 months through a widely used and validated patientoriented measure (the Carpal tunnel questionnaire) and through neurophysiological evaluation. The follow- up assessment showed significant differences in the postoperative evolution between the two groups with regard to symptoms: symptoms were less in the steroid-treated group both at 15 days (p>0.035; z=-2.9) and at two months (p<0.005; z=-2.8). This suggests that steroid irrigation of the median nerve offers benefit compared with the transverse carpal ligament release alone. This study provides clear evidence of the usefulness of the procedure in the postoperative evolution of symptoms.