Objective To explore the clinical significance of detecting serum and pleural effusions p53 antibody in patients with lung cancer. Method Serum p53 antibodies were detected in 26 patients with lung cancer

19 lung cancer patients after operation or chemotherapy and 20 patients with benign pulmonary disease as control using enzyme linked immunosobent assay. Furthermore

pleural effusions p53 antibody were detected in 5 of lung cancer patients and 6 benign pleural effusions as control. Results The Positive rate of serum p53 antibody in patients with lung cancer was 50%.The level was significantly higher than that in patients with benign pulmonary disease（4.054±6.308） IU/mL vs （0.177±0.085） IU/mL

（P<0.01）.In the patients after treatment

the positive rate was 31.6%

and the level of serum p53 antibody was （1.660±3.591） IU/mL

and there was no significant diference between the patients with benign pulmonary disease and normal individuals（P>0.05）.In benign pleural effusions control

the level of p53 antibody was （0.398±0.443） IU/mL

which was higher than the serum control

but there was no significant difference between them（P>0.05）. In lung cancer patients

detection of serum p53 antibody-positive rate was 60.0%

and the positive rate was 80.0%.Pleural effusions p53 antibody was （15.510±8.813） IU/mL

which was higher than benign control

and there was significant difference between them（P<0.01）.Conclusion Detection of serum and pleural effusion p53 antibody contributes to the diagnosis and differentiatin of benign and malignant pulmonary diseases. The method is simple and specific. Serum p53 antibody may be a marker of the lung cancer and the production of p53 antibody may be the early character of the lung cancer and the badness prognosis factor. So the detection of p53 antibody is potent for predicting recurrence and evaluating therapeutic effect. The detection of pleural effusions p53 antibody is more sensitive than that of serum.