This study was conducted to examine the effects of alterations in water temperature (WT) on biochemical and immunological factors in the hemolymph of the abalones, Haliotis gigantea and H. discus discus. The abalone were exposed to various WT; 18, 20, 22, 24, 26 and 28℃ for 96 hours. In biochemical factors, total-protein (TP), glucose, magnesium (Mg), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not significant changes in hemolymph of H. gigantea and H. discus discus. But calcium was significantly increased by high WT (≥ 24℃). In immunological factor, The phenoloxidase (PO) activity was decreased in hemolymph of H. gigantea and H. discus discus exposed to high temperature (≥ 22℃) compared to the control (P < 0.05). Whereas alkaline phosphatase (ALP) was not significantly changed. These results suggested that high temperature adversely affects the immunity of H. gigantea and H. discus discus.