Copper, zinc, magnesium, calcium and iron were measured in serum and lung tissue - tumor mass and histologically nonneoplastic tissue - from lung cancer patients and compared with serum concentrations in healthy subjects and control lung tissue obtained from patients with nonmalignant lung disease. Lung cancer patients showed a significant increase in serum Cu and Cu/Zn ratio levels and decrease in serum Zn and Fe concentrations. These findings were correlated with TNM stage of the disease, but not with histologic type of tumor. Malignant lung tissue showed a higher level of Cu, Ca, Mg, and Cu/Zn ratio and lower Zn level than that found in control samples, as well as an increase in Cu, Mg and Cu/Zn ratio concentrations with regard to histologically nonneoplastic tissue samples from the same patient. Tissue concentration of trace metals was not significantly influenced either by histologic type of tumor or clinical TNM stage. Significant correlation coefficients between serum and tissue trace metal levels were not found.