To investigate the role of metastasis suppression gene (nm23) in the development and progression of human lung cancer, the mRNA expressions of nm23-H1 and nm23-H2 genes in a series of pulmonary tissues collected at various sites and with different properties were studied with slot blot hybridization. According to the observations on the normal pulmonary tissues, benign lesions, para- and non-cancer tissues, primary cancer and metastatic lymph nodes, there was a tendency of mRNA expression reduction of nm23-H1 and nm23-H2 genes. Among them, nm23-H2 mRNA expressions in lung cancer tissues were significantly decreased when compared with normal pulmonary tissues (P < 0.05), and nm23-H1 and nm23-H2 gene expressions in metastatic lymph nodes were both reduced, compared with those in normal pulmonary tissues (P < 0.05). There was no significant correlation between nm23 gene expression and lymph node metastasis in lung cancer. The results implied that reduction of nm23 gene expression might be associated with the development of lung cancer, but no evidence of metastasis suppression by nm23 gene was revealed in this study.