AIM: To investigate the relationship among MCP-1 and monocyte chemoattract protein activity (MCA) and pathogenesis of lung cancer. METHODS: 173 patients were involved in the study and divided into three groups: group A: lung cancer group (60 patients); group B: benign lung disease group (55 patients) and group C: healthy control group (58 patients). MCP-1 level and MCA in bronchoalveolar lavage fluid (BALF) were measured. RESULTS: The concentration of MCP-1 and MCA in BALF in group A were much higher than those in group B and group C (P