The expression of basic fibroblast growth factor (bFGF) and fibroblast growth factor receptor (FGFR) mRNA was examined in gastric carcinomas by immunohistochemistry and in situ hybridization, respectively. In the 20 advanced carcinomas examined, bFGF was found in 14 (70.0 per cent) and was confined to the tumour cells, whereas FGFR mRNA was demonstrated in 12 (60.0 per cent) and seen in both tumour cells and endothelial cells. The bFGF and FGFR mRNA-positive carcinomas were larger, were more frequently classified as undifferentiated adenocarcinoma, more frequently invaded the serosal layer, and had a higher rate of lymph node metastases than the bFGF and FGFR mRNA-negative carcinomas. Patients with bFGF and FGFR mRNA-positive carcinomas appear to die earlier than those with bFGF and FGFR mRNA-negative tumours. The values for the carcinomas that were positive for either bFGF or FGFR mRNA fell between these two groups. The findings suggest that the autocrine/paracrine bFGF/FGFR channel is associated with undifferentiated gastric carcinomas and may lead to a poorer prognosis.