To investigate the change of plasma D-d imer in patients with chronic pulmonary heart disease. The plasma was measured in 36 patients with chronic pulmonary heart disease and in 25 controls .Results:The D-dimer level as significantly higher in the before treatment patients than in the after treatment patients (P<0.0l ). Conc luslons: D-dimer can be used in diagnosis of .Thrombi in small pulmonary arteri e s andarterioles.