The MTA1 gene is a recently identified metastasis-associated gene which has been implicated in the signal transduction or regulation of gene expression. We examined the mRNA expression levels of the MTA1, the human homologue of the rat mta1 gene in non-small cell lung cancer (NSCLC). Expression of MTA1 messenger RNA was evaluated by reverse transcription polymerase chain reaction (RT-PCR) in 74 non-small cell lung carcinoma samples using LightCycler. The data was analyzed in reference to clinicopathological data. There was no relationship between MTA1 gene expression and age and gender. MTA1/GAPDH mRNA level in stage II-IV NSCLC (3.465+/-3.675) was significantly higher than the level in stage I NSCLC (1.614+/-2.434, P=0.0153). MTA1/GAPDH mRNA levels in T4 NSCLC (4.377+/-4.169) was significantly higher than the level in T1 NSCLC (1.966+/-2.148, P=0.0351) and in T2 NSCLC (2.048+/-1.899, P=0.0269), respectively. MTA1/GAPDH mRNA level in NSCLC with lymph node metastasis (4.242+/-3.758) was significantly higher in NSCLC without lymph node metastasis (P=0.0169). Our results show that the expression of the MTA1 gene is closely related to invasiveness and metastasis in NSCLC. The gene MTA1 could thus potentially provide information on the mechanism of cancer invasion and metastasis.