Vapor-liquid equilibrium at 94 kPa has been determined for the binary systems methyl 1,1-dimethylethyl ether (MTBE) + methyl ethanoate and oxolane + heptane. The binary system MTBE + methyl ethanoate deviates moderately from ideal behavior, behaves almost like a regular solution, and presents an azeotrope that boils at 323.34 K and contains 62.1 mol % MTBE. The system oxolane + heptane shows moderate deviations from ideality and does not present an azeotrope. The activity coefficients and boiling points of both binary systems were well correlated with their composition by the Redlich-Kister, Wohl, Wilson, UNIQUAC, NRTL, and Wisniak-Tamir equations.