Objective: Anaplastic lymphoma kinase (ALK) gene rearrangements represent an important predictive marker and promissing therapeutic target in small subset of non-small cell lung carcinomas (NSCLC). Immunohistochemical (IHC) screening of ALK abnormalities in NSCLC was reported to have variable reliability. We analyzed association between ALK immunoreactivity and increased number of ALK gene copies often seen in NSCLC. Method: We examined 10 clinically selected EGFR negative lung adenocarcinomas. ALK protein expression was detected by IHC using antibody clone ALK1 (Dako). ALK gene status was assessed by fluorescent in situ hybridization using LSI ALK Dual Color Rearrangement probe (Abbott) and SPEC ALK/EML4 TriCheck probe (ZytoVision). Results: Increased ALK gene copy number was identified in 7 cases, 3 of them showed cytoplasmic ALK positivity. In 2 of these cases we detected rearrangement of ALK locus, once represented by ALK-EML4 fusion combined with more complex cytogenetic abnormalities. Remaining third ALK + case was negative for ALK rearrangement. Conclusion: IHC seems to be useful method for initial screening of ALK rearrangements in NSCLC. There is no clear association between ALK protein expression and number of ALK gene copies. Prognostic relevance of ALK copy gains or amplification in lung adenocarcinomas remains to be determined, together with role of ALK-inhibitors in those cases.