Four isozymes of alkaline phosphatase (AP) were purified from Elephas trogontherii (Steppe elephant) from different locations in the bone (outer and inner peripheral, cytosolic, and integral) using Sephadex G-200 gel filtration and TEAE-cellulose anion-exchange chromatography. The specimen was obtained from Erzurum Museum and its age was approx. 0.3-0.5 million years old. No fungi or bacteria were present in the bone sample. The enzyme activity was determined by using p-nitrophenylphosphate as a substrate. SDS-PAGE of all the isozymes gave a single band at the same location. The molecular mass of the four isozymes as determined by using gel filtration was about 60 kDa. Optimum pHs for the four isozymes were between 8-8.5. The optimum temperatures of the isozymes were: outer peripheral, 37.5 degrees C, cytosolic, 37.5 degrees C, inner peripheral, 35 degrees C and integral, 40 degrees C. The values of V(max) and K(m), as well different optimum temperatures indicated that isozymes were structurally different.