Ulva lactuca and Carolina mediterrnean were collected from Balteem Coast of Egypt. These two algae represented the most common species in two major divisions Chlorophycophyta and Rhodophycophyta which occur in Balteem coast. Treatment of both algae with CdCl₂ at various concentrations (50-250 μmol) resulted in an increase in the activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase(APX, EC 1.11.1.11)and glutathione reductase (GR, EC 1.6.4.2). The increase in the activities of the four enzymes was proportional with the lower CdCl₂ concentrations. However, the higher concentrations (200 and 250 μmol) of CdCl₂ resulted in reduction of enzymes activities in both algae. In addition, CdCl₂ increased the reduced glutathione (GSH) and decreased the oxidized glutathione (GSSG) contents of both algae. Also, the contents of proline and glycine betaine (GB) as well as lipid peroxidation increased with the lower concentrations of CdCl₂ and decreased at the higher concentrations However, lipid peroxidation increased continuously with increasing CdCl₂ concentrations.