Öz Antiviral and antitumoral effect of L-ascorbate (L-AsA) / Cu (II) have been established. We studied the antibacterial effect of L-ascorbate / Cu (II) and its action on the bacterial celi membrane. Oxidation products of ascorbate (AsA) produced in the presence of Cu (II). It has been known that these oxidation products cause breaks in protein and nucleic acids. They also lead lipid peroxidation. Effects of different concentrations of AsA + CuCl2 on grovvth of Escherichia cali and Bacillus subtilis were investigated. Also subtoxic concentration of AsA / Cu (II) that affect bacterial growth were established. It was found that the inhibitory concentration for B. subtilis was 4 mM AsA +100 |Ll M CuCl2 and E. coli was 8mM AsA+lOOJlM CuClD. The growth of bacterial cells were follovved spectrophotometrically. Also viable celi counts were made. Bacterial membranes isolated by Lysozyme-EDTA method to show changes caused in membranes. Also membranes isolated from control cells and bacteria grown in AsA+CuCf medium were applied on SDS-PAGE to show the changes occured in the membranes.