The toxic effects of ethanol (EtOH), indomethacin (IND) and their combination were studied in vitro. The experiments were performed on freshly isolated gastric mucosal mixed cells and two types of stable cultured cells: Sp2/0-Agl4, which is a non-secreting mouse myeloma cell line, and Hep G2, which is a human hepatocellular carcinoma cell line. EtOH decreased the viability of all types of cells in a concentration-dependent manner. At all concentrations, the EtOH caused a greater decrease in the viability of gastric mucosal cells than in the viability of Sp2/0-Agl4 cells. IND had no effect on the viability of the cultured cells, when this was employed without any other aggressive factor, such as EtOH. When used in combination, IND aggravated the EtOH-induced cell injury. These results show that the endogenous prostaglandins may play a role in the maintenance of cell integrity in all three types of cells.