The aim of this investigation was to develop an experimental model for studies on the significance of fibrin deposition for wound healing. Systemic defirbinogenation with Arvin was used to achieve abnormal fibrin deposition in subcutaneously implanted cellulose sponges. The formation of granulation tissue in the sponges was studied histologically. Arvin injections resulted in a rapid decrease in plasma fibrinogen concentration with a concomittant rise in fibrin-degradation products. No change in FXIIIa activity was seen. During defibrinogenation an abnormal fibrin deposition was found in the sponges. The fibrin strands appeared irregular and disrupted. The number of fibroblasts and collagen fibrils was reduced in granulation tissue formed during defibrinogenation. The model used seems to allow controlled studies on the significance of fibrin deposition for wound healing. Defibrinogenation was found to influence granulation tissue formation.