A real-time PCR technique with automated computerized analysis (TaqMan ) was tested to detect K-ras mutations in 66 patients suffering from NSCLC. This technology is characterized by high reproducibility of data and a time-saving analysis procedure. In 11% (7/66) of the tumour specimens and 2% (1/58) of adjacent tumour-free lung specimens a K-ras codon 12 mutation was detected. In adenocarcinomas containing > or =40% tumour cells, however, K-ras mutations were seen in 25% of the cases. The point mutations detected in tumours were GGT right curved arrow TGT in five cases and GGT right curved arrow GTT in two cases. As compared with immunohistochemical parameters, the K-ras mutated group was characterized by a c-erbB-2 negativity (p=0.04) and a smaller number of c-erbB-3 (p=0.02) positive cases. EGFR, bcl-2, p53, Ki-67 and p120 expression did not differ significantly. Determination of the K-ras point mutations by automated TaqMan PCR in NSCLC tumour specimens is feasable and highly specific. Due to its high throughput capacity this method represents a valuable tool for routine screening.