Thermal responses of adipose tissue to high intensity focused ultrasound (HIFU) were quantitatively evaluated for effective clinical lipolysis. A single-element HIFU transducer (4MHz and 4.5mm focal depth) was used in a linear motion to thermally treat the tissue at various acoustic energy densities and treatment gaps. Both interstitial temperature rise and denatured lesions increased with the energy density (up to 21.1 + 1.9K and 0.40 + 0.15mm2). No thermal overlapping was observed due to selective application of the ultrasonic beams. The optimization of noninvasive HIFU treatment parameters may ensure clinical outcomes of HIFU-assisted lipolysis in terms of efficacy and safety.