An apparatus and method for treating subcutaneous tissues using acoustic waves in the range of low acoustic pressure ultrasound waves is disclosed. The method includes injections of enhancing agents, wherein disruption of subcutaneous tissues and subcutaneous cavitational bioeffects are produced by ultrasound waves having a power that will not produce tissue cavitation in the absence of the enhancing agents. The apparatus and method of use is useful for treatment of subcutaneous abnormalities including cellulite, lipomas, and tumors.