The antigen levels of plasminogen activators (PAs), tissue-type PA (t-PA) and urokinase-type PA (u-PA), were measured in extracts from 30 gastric carcinomas and corresponding normal gastric mucosa. The t-PA level was significantly higher in normal mucosa than in cancer tissue, while the u-PA level was significantly higher in cancer tissue. The u-PA level increased with increasing tumor stage, and there was a significant difference between early and advanced cancer. The u-PA level also increased with the degree of nodal involvement, and it was higher in undifferentiated tumors than in well-differentiated ones. It was higher in cases with venous invasion, liver metastasis or peritoneal dissemination than in cases without these features.