['To investigate the effect of high glucose on hydroperoxide (H2O2)-induced apoptosis in cultured bovine aortic endothelial cells (BAEC).', 'BAEC were cultured and passaged in normal glucose (5.5 mmol.L-1, NG) and high glucose (25 mmol.L-1, HG). Morphologic changes and quantification of apoptotic cells were determined under fluorescence microscope after H2O2-treated BAEC for 24 h with Hoechst 33258 staining. DNA fragmentation was visualized by agarose gel electrophoresis. The expression of phospho-p38 Ca(2+)-calmodulin dependent protein kinase (CCDPK, formerly called MAPK) was measured by Western blotting.', 'H2O2 elicited typical apoptotic morphologic changes (chromatic condensation, nucleus fragmentation). At 100 -300 mumol.L-1, both NG- and HG-BAEC incubated with H2O2 for 24 h increased cell apoptosis and phospho-p38 CCDPK expression in a concentration-dependent manner. In HG-BAEC, H2O2 induced DNA fragmentation at a lower concentration than that in NG-BAEC, and the apoptotic cell count in HG-BAEC was also higher than that of NG-BAEC (P < 0.05). Similarly, the expression of phospho-p38 CCDPK induced by H2O2 was up-regulated in HG-BAEC (P < 0.05).'] Does high glucose enhance H2O2-induced apoptosis in bovine aortic endothelial cells?