The purpose of this research was to compare Aquasonic ® and T-prep ® gel, a 1% methyl nicotinate preparation, in their ability to increase the temperature of soft tissue when used with 3MHz ultrasound.Thirty healthy participants (21–40 years of age) completed this IRB approved study. In the prone position, a 26gauge, 4cm thermistor was inserted 2.5cm deep in the posterior calf. An OmniSound Unit was used to administer a 3MHz treatment at 1.0w/cm 2 in a 6cm 2 -defined area with a 2cm 2 transducer. Temperature measurements were taken every 30s for 15min. On one calf, 5cm 3 of Aquasonic ® gel was used as the coupling medium and on the other, 5cm 3 of T-Prep ® gel was used.A repeated measures ANOVA was used to detect a significant difference over time but no significant difference was found between the coupling mediums. After 15min, the T-Prep ® gel contributed to a 1.8°C overall temperature increase compared to a 1.5°C increase with Aquasonic ® gel.The results of this 3MHz study revealed that the acoustic transmission characteristics of the T-Prep ® and Aquasonic ® gels were similar at increasing tissue temperature at a depth of 2.5cm. Given that there are numerous conducting mediums that have been shown to limit the transmission of ultrasonic waves, T-Prep ® may be an option to Aquasonic ® gel when tissue heating is desired. Further research on the depth of heating with T-Prep ® gel would be appropriate.