Liquid liquid equilibrium (LLE) data for the soybean oil biodiesel (BIO-SO) + ethanol + water and castor oil biodiesel (BIO-CO) + ethanol + water systems at (298.2 and 333.2) K and atmospheric pressure were determined by gas chromatography and volumetric Karl Fischer titration. The degree of consistency of the experimental LLE data was ascertained by applying the Hand and Othmer-Tobias correlations. Ethanol distribution coefficients and water selectivity were evaluated for the immiscibility region. The experimental data were also compared with the values correlated by the NRTL and UNIQUAC activity coefficient models. For all systems studied, the average deviations found for the UNIQUAC model are larger than those found for the NRTL model.