Synthesis of the Azotobacter chroococcum invertase was found to be dependent on sucrose or raffinose in the growth medium. The activity of this invertase was slightly inhibited by glucose. Fructose, which by itself did not affect the enzyme activity, protected invertase from glucose inhibition. Per cent residual activity plotted against glucose concentration, and Hill plot indicated that this monosaccharide binds to one interacting site of the enzyme. The results show that regulation of this prokaryotic enzyme clearly differs from that of eukaryotic orgnisms.