Injury to a peripheral nerve is followed by local synthesis and release of neurotrophic factors of importance for the regeneration process. This concept was adopted for repair of transected human median and ulnar nerves in the forearm. As an alternative to conventional microsurgical repair of the nerve trunk, silicone tubes of appropriate size were used to enclose the injury zone, intentionally leaving a gap measuring 3-4 mm between the nerve ends inside the tube. The early results from a prospective, randomized, clinical study comparing this principle with conventional microsurgical technique for repair of human median and ulnar nerves, is presented. Eighteen patients (14 men and 4 women), aged 12-72 (mean, 29.5) years, were randomized to either tubulization (11 cases) or conventional microsurgical repair (7 cases). A battery of tests for sensory and motor functions of the hand were carried out at regular intervals for up to 1 year after surgery. The results show no difference between the both techniques, with the exception of perception of touch, which showed a significant difference (p < .05) at the 3-month checkup in favor of the tubulization technique. At re-exploration 11 months after the initial procedure (1 case), the former gap was replaced by regenerated nerve tissue in direct continuity with the proximal and distal parts of the nerve trunk, the exact level of the former injury being impossible to identify. Study data demonstrate an intrinsic capacity of human major nerve trunks to reconstruct themselves in a preformed space when an optimal environment is offered and the surgical trauma is minimized.