A new clot-suturing Technique (using high-concentration fibrinogen solutions) for water-tight closure of the dura is reported. Six dogs underwent laminectomy of the thoracic spine with medial longitudinal incision in the chordal dura. After the dural split had been sealed with natural tissue adhesive and closure of the wound in layers, the animals were sacrificed at intervals of 1 to 21 days postoperatively and the chordal segments involved were removed and histologically examined. Early fibrinolysis of the clot was prevented by adding a natural proteinase inhibitor and factor XIII concentrate to the clotting substances. Histological analysis showed that healing was almost complete after 2 weeks, with delicate connective tissue overgrowing the dural split. After complete reabsorption of fibrin, the originally abundant absorbent granulation tissue had largely disappeared. Among the satisfactory results of fibrin suturing are optimum healing tendency in the fibrin-sutured region, absence of tissue irritation and neurotoxicity, which are known attributes of the synthetic alkl-cyano-acrylate tissue adhesives.