Objective:To investigate the expression level of adrenomedulin(ADM)in lung cancer patients,the relationship be- tween ADM and the pathological type and stage of lung cancer.Methods:We determined the content of ADM in plasma of 20 healthy adults,24 non-lung cancer patients and 61 lung cancer patients by use of radioimmunoassay.Results:The content of ADM in the plasma of healthy control group was 30.25±8.12 pg/L,lung cancer group was 40.17±19.23 pg/L,there was significant difference between them(P<0.05) ;The content of ADM in the plasma of non-lung cancer group was 27.94±6.75 pg/L,compared with lung cancer group,there was significant difference(P<0.01 );Small cell lung cancer group compared with non-small cell lung cancer group,the content of ADM in plasma had no significant difference(P>0.{)5) ;Ⅰ-Ⅲstage of lung cancer group compared withⅣstage group,the content of ADM in plasma had significant difference(P<0.05).Conclusion: The expression level of ADM in plasma of lung cancer increased,the expression level of ADM was correlated with the stage of lung cancer and distant metastasis,No correlation was found between ADM level and the pathological type of lung cancer. Therefore,detecting ADM in plasma had great value in lung cancer diagnosis and staging,and provided a new way to lung cancer diagnosis.