Twenty-three dogs underwent a complete transection of the spinal cord at L 1 level. Section was followed in eighteen animals by reconstruction effected through suture of the arachnoide with the aid of monofilament 10 X 0 thread. The operation was in all cases concluded by an osteosynthesis with metallic material in order to prevent any movements in the operated site, and a tight dural closure was achieved in order to prevent propagation of any epidural hematoma or secondary granuloma. This technique did not prevent an unfavorable evolution of the suture, which demonstrated three different morphological features:--necrosis of the spinal cord cut ends with secondary formation of a transverse cyst;--secondary infiltration of the operated focus by a fibrous scar growing from the inner aspect of the dura;--failure of axon regeneration through this fibrous block in spite of noteworthy proliferation of axons coming from the dorsal roots. A critical analysis of those results led to a comparaison with various previous works on the same subject. The most recent of these works have led to promising prospects which need confirmation.