AMP deaminase (EC 3.5.4.6) from anterior lobe of bovine pituitary has been purified for the first time. Six molecular forms of the enzyme were eluted from phosphocellulose Pll with a KC1 concentration gradient. By two stage gel chromatography individual molecular forms were purified to electrophoretic homogeneity. Comparison of some physico-chemical and kinetic properties of the preparations obtained showed high similarity of their properties to those of AMP deaminase from other animal tissues already described. All the isoforms were found to be Zn2+-dependent.