We report one case of ligneous periodontitis, which is a clinical sign of hypoplasminogenemia. It appears as massive, painless ulcerated gingival enlargements and alveolar bone destruction in the affected area. The course of the disease is progressive and typically ends with early loss of teeth. At present, no efficient treatment option seems to be available. To investigate the cause of the rapid bone destruction in this disease, gingival tissue specimens were taken from one patient and a healthy control patient to compare the function of fibroblastic cells. Our results showed that diseased fibroblasts (1) reorganized collagen lattices more rapidly than normal cells, (2) demonstrated a greater overall production of pro and active matrix metalloproteinase-2 (MMP-2) and increased activation of this protease, and (3) showed a more active phenotype than healthy fibroblastic cells. From these preliminary results, there seems to be increased MMP-2 production and activation, which might be one compensatory (but insufficient) mechanism for the decreased (plasmindependent) pericellular fibrinolysis in plasminogen-deficient patients. Further studies on this subject should evaluate the exact pathomechanism of plasminogen on this enzymatic bone and connective tissue destruction. Schlagwörter: hypoplasminogenemia, ligneous conjunctivitis, ligneous periodontitis, pseudomembranous lesions, treatment options, type I plasminogen deficiency