The ultrasonic amplitude absorption coefficient has been determined in aqueous solutions of four molecular weights (73 000, 186 000, 370 000, and 2 000 000) of dextran, a linear α (1 → 6) anhydroglucose polysaccharide of biological origin, over the frequency range 3–69 Mc/sec at 22°C. It is found that the concentrationfree absorption spectrum exhibits a remarkable similarity to that of aqueous solutions of beef hemoglobin. The latter finding leads to the conclusion that ultrasonic absorption in tissues is not dominated exclusively by constituent proteins and that the contribution to such absorption by molecular structures lacking tertiary configurations may be considerable.