Cyclic changes in the phosphatases were studied histochemically in the uterine complex of the female Suncus. Alkaline phosphatase activity showed constant and predictable changes in the various phases of the cycle with the maximum activity during metaestrus. Acid phosphatase and ATPase activities also showed constant changes with moderate activity during diestrus and proestrus but with maximal activities during estrus and metaestrus. No proper localization of the enzyme is discernible in the case of G-1-Pase and G-6-Pase.