Factor XIII (FXIII) links soluble fibrin monomers and collagen fibres to stable fibrin connections. Deficiency of FXIII, caused by dyspoiesis or increased consumption, results in a bleeding tendency and wound healing complications. Although the decrease of FXIII and successful replacement in patients with wound healing complications after surgery have been described by several authors, it is rarely considered that patients with autoimmune diseases, bleeding or healing complications may suffer from FXIII deficiency. We report a patient with severe psoriasis vulgaris generalisata with large, painful erythemas, bleeding tendency, joint contractions and infirmity, whose FXIII activity was 19%. After successful replacement the bleeding tendency vanished, and a marked improvement of skin and joint mobility allowed mobilisation and administration of physical therapy, whereby some independence and mobility were restored to the patient.