Expression of MCAM is observed in a variety of human malignancies. We aimed to determine the rate of MCAM expression in our non-small cell lung cancer (NSCLC) collection and to clarify its correlation with clinicopathological parameters and patient survival. 85 NSCLC were analysed immunohistochemically using a monoclonal MCAM antibody (clone N1238) on an NSCLC tissue micro array. The staining was semiquantitatively scored. We found MCAM expression in 51% of NSCLC, preferentially squamous cell carcinomas (p=0.004). No other correlations to tumour size, grade, or stage were found. Univariate survival analysis showed no significant differences of MCAM positive and negative tumours. In adenocarcinomas however, MCAM positivity was significantly associated with shorter patient survival (p=0.016). We conclude, that MCAM is expressed in a high proportion of NSCLC and might be predictive of shortened patient survival in adenocarcinomas of the lung. Colour figure can be viewed on http://www.esacp.org/acp/2003/25-2/kristiansen.htm