The dielectric spectra corresponding to the static regime of dimethyl sulfoxide + water mixtures were recorded in the whole concentration range and in the temperature range from (253.15 to 333.15) K. For the mixtures rich in DMSO (0.60 < x(DMSO) <= 1, x = mole fraction) and rich in water (0 <= x(DMSO) < 0.1), it was possible to perform the investigations both in the liquid and solid phases of the samples. The determined melting temperatures were compared to the data available in the literature. The deviation from the additivity of the measured static permittivity of DMSO + water mixtures shows a maximum for x(DMSO) approximate to 0.35, indicating formation at that concentration of intermolecular entities (most probably they are 1DMSO.2H(2)O hydrogen-bonded complexes) of a relatively enhanced polarity.