Abstract： Objective To investigate the relationship between the expression of glucose regulated protein 94 (GRP94) at the level of mRNA and protein in vivo and in human lung cancer. Methods RT-PCR, immunohistochemistry and/or Western blot were used in 54 cases of lung cancer tissues and corresponding normal lung tissues.Results There was a significant overexpression of GRP94 mRNA and protein in lung cancer tissues as compared with lung normal tissues. In lung cancer tissue, the relative level of GRP94 mRNA as evaluated by RT-PCR was 3.48±2.06, the level of GRP94 protein as evaluated by immunohistochemistry was ++ to +++, and by Western blot was 256.7±80.6. In lung normal tissue, the relative level of GRP94 mRNA was 2.01±1.83, the level of GRP94 protein was + to ++ and 108.1±42.3. The differences in expression of GRP94 between the two tissues were significant (P<0.05). Furthermore, the over-expression of GRP94 in the lung cancer tissues was correlated to grade of differentiation and stage of tumors. There was stronger expression in poor-differentiated tumors than in mild-to-high differentiated tumors (P<0.05). There was also a stronger expression in stage Ⅲ than in stage Ⅰ and Ⅱ tumors (P<0.05). No statistically significant difference was found among various pathological types of tumors.Conclusion GRP94 was related with the occurrence, differentiation and progress of human lung cancer. Ascertaining the levels of GRP94 mRNA and protein may be valuable in evaluating the grade of differentiation and clinical stage of human lung cancer.