By analysing the frequencies of positive and negative HER2 expression, we established that positive HER2 overexpression (2+, 3+) in patients with lung adenocarcinoma amounts to 7.4% for HercepTest Dako, and 2.7% for Ventana anti-HER2/neu (4B5). This evidence concerns the gene ERBB2 and lung adenocarcinoma.