For the 11 binary liquid systems [xC(6)H(5)OCH(3) + (1 - x) {C6H6, or C6H5CH3, or 1,2-C6H4(CH3)(2), or 1,3-C6H4(CH3)(2), or 1,4-C6H4(CH3)(2), or C6H5C2H5, or 1,2,4-C6H3(CH3)(3), or 1,3,5-C6H3(CH3)(3), or C6H5CH(CH3)(2)}] and [xC(6)H(5)CHO+ (1 - x) {C6F15C2H5, or 1,3,5-C6H3(CH3)(3)}], excess molar enthalpies HE have been measured as a function of mole fraction x of either phenylmethylether (PME, anisole, methoxybenzene, C6H5OCH3) or benzaldehyde (BA, C6H5CHO) at the temperature T = 298.15 K and atmospheric pressure. For these measurements, an LKB differential flow microcalorimeter equipped with two computer-controlled h.p.l.c. piston pumps (from Gilson) was used. For the mixtures of PME with an aromatic, the H-E-curves are all positive and rather small, and more or less parabolic; {PME + 1, 3, 5-trimethylbenzene (mesitylene)} exhibits the largest values: H-E (x = 0.5) = 358 J mol(-1). The excess molar enthalpies of the mixtures of benzaldehyde with an aromatic are also all positive and rather small [e.g., for (BA + 1, 3, 5-trimethylbenzene) H-E (x = 0.5) = 316 J mol(-1)] though somewhat more skewed than those of the corresponding mixtures with PME.