The ultrasonic absorption of aqueous solutions of salmon sperm deoxyribose nucleic acid (DNA), molecular weight of the order of 106, was determined as a function ofpH in the neutral and acidic regions over the frequency range 5–50 MHz at 25°C. The viscous relaxation frequencies appear to be well below 1 MHz. At neutralpH values, viscosity and molecular conformation appear to contribute little in determining the ultrasonic absorption spectrum. The DNA solution absorption spectrum appears to be similar to that of globular protein aqueous solutions implying that the mechanisms may be the same. The ultrasonic absorption acid titration curves for DNA exhibit maxima aroundpH 2.6 and 12 [J. Chim. Phys.66, 81 (1969)] which can be attributed to either or both hydrogen bond transfer and proton transfer as the double helix DNA molecule denatures.