The author attempted to observe the cellose acetate microzone electrophoretic patterns, quantitative estimation, and histochemical localization of alkaline phosphatase from the sera and various organ tissues. in rabbit. In the electrophoretic analysis the tissue ALP from the liver (α1 and α2, lung (α2/β,β, and, β/r), bone (α2, α2/β, and β), kidney (α2, α2/β, β/r and γ), Iymph node (α1, α2, α3/β, and β), spleen (α2/β and β), and intestine (α2/β and β) showed the fractions of the high activity, while the heart and skeletal muscle did not show the any fraction of ALP. In the quantitative measurements of tissue ALP activity per gram unit extract the kidney ALP showed the highest level (49.5 Bessey-Lowly units), and the activity of the skeletal muscle ALP was the lowest (1.5 B.L. units). From the histochemical localization the tissue ALP was confirmed mainly in the biliary canaliculi of the liver, the convoluted tubules of the kidney, the intestinal and bladder mucosa, the bronchial and bronchiolar epithelium and the alveoli of the lung, white pulps of the spleen, the cortex and medulla of the adrenal gland, the lymph node and the brain tissue respectively, while there was no ALP activity in the heart and the skeletal muscle.