Aim of this study was the determination of new markers for the diagnosis of lung cancer. 61 patients with non-small cell lung cancer (NSCLC) and 42 controls were enrolled. In the NSCLC patients the following markers were increased: H2O2 in exhaled breath condensate, pentane, hexane, nonenal, trans-2-heptanal, trans-2-nonenal in exhaled breath, while pentanal was decreased. Using multivariate statistical models, a sensitivity of 73.8% and a specificity of 76.8% were calculated. This study shows that with this non-invasive test followed by a most powerful test on positives (e.g. PET) it is possible to decrease the number of false positives.