Matrix metalloproteinases (MMP's) 3, 10 and 11 (also known as stromelysins 1, 2 and 3, respectively), and matrix metalloproteinase 7 (also known as matrilysin), produced by stromal fibroblast-like cells in the vicinity of various malignancies, are suspected to have an ability to degrade components of extracellular matrix, thus promoting spread of the tumor. MMP's also have been found in epithelial tumor cells in various cancers. Tissue sections from 95 cases of non-small cell lung cancer (NSCLC) were immunostained with antibodies against MMP 3, MMP 10 and MMP 11 and sections from 99 cases of NSCLC were immunostained with an antibody against MMP 7. Cytoplasmic immunoreactivity in the tumor cells was semiquantitatively scored for intensity and distribution and correlated with tumor type, tumor grade, stage, tumor size, lymph node positivity, metastasis and survival. Overexpression of MMP 10 and MMP 11 correlated with higher grade for NSCLC (p = 0.029 and p = 0.016, respectively), and also in a subset of adenocarcinomas (AC) (p = 0.015 and p = 0.009, respectively). Also, MMP 10 and MMP 11 correlated with lymph node involvement in NSCLC (p = 0.025 and p = 0.027 respectively). No correlation was found for MMP 3. Overexpression of MMP-7 correlated with tumor stage (p = 0.0001) and was associated with adverse clinical outcome (p = 0.0001) in NSCLC and also in separate squamous cell carcinoma (SCC) (p = 0.003) and AC (p = 0.004) tumor groups.