Lung cancer, of which non-small-cell lung cancer (NSCLC) constitutes about 80%, is the greatest cause of cancer-related death worldwide. Serum tumour markers may be helpful in early diagnosis, in the initial assessment of the progress of the disease and in monitoring of the tumour growth or tumour volume reduction. Recent studies have focused on a new family of markers--hematopoietic growth factors. Some clinical investigations have shown autologous production of stem cell factor (SCF) in various human cell lines derived from lung cancer and the expression of SCF mRNA in these lines. In this study, the serum level of SCF was measured using a sensitive sandwich ELISA system in 34 patients with non-small-cell lung cancer before and 10, 30, 90, 180 and 270 days after operation. Additionally common accepted tumour markers such as CEA and CYFRA 21.1 were also assayed. Preoperative level of SCF was increased in cancer patients in comparison to the normal sera. Concentrations of SCF and CYFRA 21.1 were decreased on 10th day, but CEA on 30th day after surgical treatment, although upon comparison of pre- and postoperative tumour markers serum levels significant difference was observed for SCF and CYFRA 21.1 (p < 0.05). Levels of SCF were increased in 79%, CEA in 62% and CYFRA 21.1 in 51%. The diagnostic sensitivity of SCF were related to the stage of the disease and the combined use of two markers increased the sensitivity compared with the use of only one. These results suggest that SCF may be useful in the diagnostic and monitoring of patients with NSCLC.