Liquid-liquid equilibrium (LLE) data for the ternary systems water+ 1-butanol +methyl methacrylate or butyl methacrylate or isobutyl methacrylate were determined at atmospheric pressure and at 288.15 K and 318.15 K. From these new LLE data, we can find that very small amounts of the organic compounds were found in the aqueous phase, while water dissolved appreciably in the organic-rich phase. The reliability of the experimental tie-line data has been tested through the Othmer-Tobias and Bachman plots. The experimental data were also compared with the values correlated by the NRTL and UNIQUAC models. Good agreement was obtained with these models. In general, the average deviations from the UNIQUAC model are slightly smaller than those from the NRTL model. (C) 2007 Elsevier B.V All rights reserved.