In order to establish effective procedures for chromosome manipulation in Haliotis gigantea and H. discus, which are of enormous aquacultural potential, temperature-dependent measures of mitotic intervals (τ0) were determined. Mitotic intervals (τ0) in these abalone were determined by averaging the duration of the first and third embryonic divisions over a range of temperatures from 8 to 26℃. The relationships of each mitotic interval at two cell (τI), four cell (τII), eight cell (τIII), sixteen cell (τIV) and τ0, to temperature (T in ℃) in H. gigantea were log τI = 176.1-28.3T, log τII = 199.5-12.4T, log τIII = 236.2-12.2T, log τIV = 269.3-14.1T and log τ0 = 83.1-32.8, respectively. The relationships of each mitotic interval at τI, τII, τIII, τIV and τ0, to temperature in H. discus were log τI=104.9-13.8T, log τII = 138.3-10.5T, τIII = 172.4-10.2T, log τIV=211.3-12.2T and log τ0=85.6-33.3T, respectively. There were strong, negative correlations between mitotic interval and water temperatures for all ten temperatures in these two species (H. gigantea: Y = -138.75 logX + 341.25, R2 = 0.97; H. discus: Y = -112.33 logX + 255.22, R2 = 0.98, where Y is mitotic interval and X is temperature).