Plasminogen deficiency has emerged as a well-recognized disorder in which reduced levels of plasminogen lead to the development of pseudo membranes on mucosal surfaces, with subsequent end-organ damage of the affected tissue. Ligneous conjunctivitis is the most recognizable, well-documented, and common presentation of the clinical syndromes associated with plasminogen deficiency, although numerous other organs have been reported to be affected. Interestingly, while plasminogen deficiency was initially believed to be related to development of venous thromboembolic disease, more recent data suggest that decreased plasminogen levels may not, in and of themselves, increase the risk of thrombosis. Two types of plasminogen deficiency have been described in the literature. Type I represents a quantitative deficiency and type II a qualitative deficiency. It appears that hypoplasminogenaemia (type I deficiency) is the type most associated with pseudomembrane disease. A variety of genetic mutations has been identified recently and is reported to lead to these disorders. These defects have been identified in diverse populations, with no specific ethnic predilection. However, this disorder may have increased prevalence in areas and communities where consanguinity is more common. Despite the fact that the characteristic lesions are now better recognized and plasminogen levels are accurately and easily measured, adequate treatment of the clinical manifestations of this disorder is lacking. For ligneous conjunctivitis, a plasminogen concentrate formulated into an ophthalmologic preparation has been found to be an effective local therapy. Unfortunately, no plasminogen concentrate is currently available commercially for either systemic or local therapy.