Abstract: CC-chemokine ligand 18 (CCL18) is mainly expressed by alternatively activated macrophages and DCs and plays an important role in lung fibrosis, arthritis and other diseases. Here CCL18 was measured in sera of 31 healthy volunteers and 170 patients with lung cancer and correlated these data with histology, tumor stage and clinical parameters. Mean CCL18 serum level of the patients with non-small-cell lung cancer was 150(857) ng/ml vs. 32(61) ng/ml in the healthy control group. Patient groups differ significantly according their histology (adenocarcinoma 143(528) ng/ml vs squamous cell carcinoma 187(857) ng/ml, p<0.02). In addition, we found a significant difference between patients with lower versus higher T-stage (p<0.003). Receiver operating characteristic (ROC) analyses revealed a cutoff point of 83 ng/ml (area under the curve (AUC): 0.968; p<0.0001) to discriminate between healthy controls and non-small-cell lung cancer patients. ROC analyses to discriminate between patients, who died because of cancer related death and those who died for other reasons did not lead to a valid AUC. To stratify the tumor patients, a criterion value plot was performed leading to a point of equal sensitivity and specificity (54%) of 162 ng/ml. Patients with a CCL18 serum level higher than 160 ng/ml had a mean survival time of 623 days. In contrast, those in patients with a baseline level between 83 ng/ml and 160 ng/ml the mean survival time was 984 days (p<0.005). Survival-analysis revealed in adenocarcinoma a mean survival of 1152 days in the group below 83 ng/ml. In the median group the mean survival time was 788 days and in the group with the highest levels the mean survival time was 388 days (p<0.001). In contrast, we found no correlation between the FEV1 and the CCL18 baseline level. In conclusion, in patients suffering from adenocarcinoma increased serum CCL18 levels predict a diminished survival time