We screened samples of tumour and peripheral normal tissue for differential expression of oncogenes by using an approach of detecting the differences in expression of a number of oncogenes simultaneously. Total RNA was isolated from 29 pairs of normal and tumour tissue samples from patients with gastric adenocarcinoma. Seven pairs of primers for oncogenes most probably associated with the process of carcinogenesis in stomach including cyclin E, c-erbB-3, HGR, c-met, TDGF/cripto, FGF-4, and EGF were used for the construction of fluorescent multiplex RT-PCR. Sense primers were 5' end-labelled with a fluorescent dye. 5-7 gastric oncogenes were simultaneously analysed for overexpression. Multiplex reverse transcription with a set of unlabeled primers was followed by a PCR reaction by adding the corresponding set of fluorescent labelled PCR-primers. Expression of oncogenes was compared to GAPDH internal standard. Multiplex fluorescent RT-PCR results were analysed by capillary electrophoresis on ABI-PRISM 310 Genetic Analyzer. Differential expression of oncogene mRNAs in tumour and normal tissue was assessed by comparison of oncogene/GAPDH ratios in tumours and their peripheral normal mucosa. Our results show, that in most patients, comparing to normal tissue, we could estimate overexpression of at least one oncogene in a sample.