Experimental values are reported for the sound absorption coefficients in aqueous solutions of magnesium sulfate over the frequency range 3 to 43 megacycles. Measurements were made by an electrical method at the lowest frequency and by the pressure balance method at higher frequencies (12–43 mc). Absorption coefficients are reported as a function of frequency, concentration, and temperature. An excess absorption (relative to water) is found at the higher frequencies which cannot be interpreted by the present theory.