The aim of this study was to ana1yze T-cell lymphoma invasion and metastasis-inducing factor 1 (Tiam1) expression in 1ung cancer patients. A total of 204 patients with lung cancer tissue lesions were enrolled in the present study, along with 40 cases of normal lung tissue and 40 of normal fetal lung tissue. Tiam1 protein expression level was determined using intensity quantitative analysis, for comparison in lung cancer, metastatic, normal lung, and fetal lung tissue. The positive unit (PU) of Tiam1 was $13.5{pm}5.42$ in lung cancer,$5.67{pm}1.56$ in norma1 epithelial cells, and $5.89{pm}1.45$ in fetal lung epithelial cells. The value in the lung cancer tissue was significantly higher than that in the normal lung tissue and the fetal lung tissue (P<0.01). The Tiam1 PU values with lymph node metastasis and without 1ymph node metastasis were $15.2{pm}4.34$ and $12.5{pm}4.23$, respectively, and the difference was statistically significant (P<0.05). The Tiam1 PU values in different tumor, nodes, metastasis (TNM) stages, III-IV period, and I-II phase were $14.7{pm}4.14$ and $11.0{pm}5.34$ (P<0.05). A correlation was found between Tiam1 expression and the age of patient, tumor size, tumor type, and tumor differentiation. Tiam1 protein expression in the lung tumor tissue is significantly higher than that in the normal lung tissue and fetal lung tissue. Tiam1 expression may be closely related to lung cancer development and metastasis.