Expression of proliferation associated nuclear antigen P-105 was examined with flow cytometry in forty-three patients with advanced gastric cancer. Expression of P-105 was observed abundantly in cancer, about four times than normal mucosa, but little in normal gastric mucosa. We evaluated the expression of P-105 in cancer as P-105 intensity: mean FITC levels of G0G1 of the cancer cells/those of normal cells. The P-105 intensity did not correlate with DNA index or S-phase fraction. Furthermore, it did not correlate with histologic type, stromal type, infiltrating type, and gross appearance. However, P-105 intensity was significantly higher in the patients with hepatic metastasis, and lower in those with peritoneal dissemination than those without metastasis, respectively. From the results, it was supposed that P-105 intensity might be a useful indicator for metastatic type different from those previously reported in human gastric cancers.