Alkylsulfonate compounds act as potent allosteric inhibitors of AMP deaminase from bovine brain. The order of effectiveness as inhibitors was stearoyl->cetyl->myristoyl->lauryl->decylsulfonate. Laurylbenzene sulfonate was the most potent inhibitor of the enzyme. The I(0.5) values of alkylsulfonates, the concentrations required for 50% inhibition, were closely related to the hydrophobic parameter of the inhibitors, suggesting that the inhibitory sites of the enzyme for the binding of alkylsulfonates involve hydrophobic nature. Inhibition of AMP deaminase by alkylsulfonates and alkylbenzene sulfonate may serve for understanding the biological toxicity of this compounds as environmental pollutants.