Objective:To study the expression of Id

1

and Id

3

in human non-small cell lung cancer（NSCLC）

and to analyze its potential clinical significance.Methods:Id

1

and Id

3

were detected by immunohistochemical staining technique in paraffine-embedded specimens of 60 NSCLC cases

18 benign disease cases including 10 tuberculosis and 8 inflammatory pseudotumor（IPT）

and 12 normal lung cases

and analyzed by the lung cancer clinicopathologic characteristics.Results:There were no Id

1

or Id

3

expression in normal lung tissue

and negative to weak expression of those in benign disease tissues.In contrast

the expression of Id1 and Id

3

was obviously upregulated in NSCLC

which was significantly higher than that in benign disease（P

<

0.01）.Furthermore

the over expression of Id

1

and Id

3

was significantly correlated with lymph node metastasis and was not correlated with pathological type

the different age or the different gender of the patients.Conclusion:In NSCLC

Id

1

and Id

3

protein are overexpressed and their expression are positive correlated with lymph node metastasis.It suggested that Id

1

and Id

3

are associated with tumorigenesis

invasion and metastasis in NSCLC.Id

1

and Id

3

might be used as new markers of NSCLC for diagnosis and prognosis.