This study evaluated small heat shock proteins (sHSP) (related to alpha-crystallin) and antioxidant enzymes (POD, peroxidase and CAT, catalase) as possible biomarkers for use in toxicological studies. Biochemical responses to cadmium chloride in two Lake Baikal endemic amphipods (Eulimnogammarus verrucosus, Eulimnogammarus cyaneus) and Palearctic species (Gammarus lacustris) were compared. Our findings showed that cadmium chloride toxicity directly influenced POD activity and sHSP synthesis in all amphipod species. The Baikalean endemic and the Palearctic amphipod species responded by decreasing activity of POD and they exhibited a dose-dependent activation of sHSP synthesis. All measured parameters differed among species and depended on the species' ability to resist cadmium chloride toxicity. CAT activity in the Palearctic species responded significantly to cadmium chloride exposure; however, responses were negligible for both Baikalean species. We suggest that synthesis of sHSP, together with changes in POD activity, could be used as biomarkers for further studies of amphipod species including endemics from Lake Baikal.