We demonstrated the elevation of serum Group II phospholipase A2 (PLA2) in 56.5% of patients with cancers of digestive organs. The elevation of serum Group II PLA2 was more frequently seen in patients with advanced or metastasized cancer than in those with early cancer (66.7 vs. 35.0%). There was no correlation between serum Group II PLA2 and carcinoembryonic antigen (CEA) in these patients. A combined assay of Group II PLA2 and CEA increased the sensitivity of detection of all, early and advanced cancers from 37.1, 15.0 and 47.6% with CEA alone to 71.0, 45.0 and 83.3%, respectively.