© 2019, © 2019 Taylor & Francis Group, LLC.RF devices have frequency, power and duration setting options, it is important to make sure that the device meets the targeted values at the head output. This study was made to evaluate the RF device output value accuracy and the effects of different frequencies on the tissue heat levels. RF was applied to invitro tissues obtained from surgical operations, and invivo tissues during operations. Heat differences and depth were measured by laser/IR thermometer and thermal infrared camera. First, the output frequency and power values provided by the device were approved. Then, three three heads (monopolar, bipolar and tripolar) with three different frequencies (1,7, 20 MHz) were used. Depth of heat increase was evaluated in millimeters. The results showed that temperature increase varied between 10°C and 30°C at different depths using different frequencies. Heating of the skin with a radiofrequency device in a therapeutic dose is possible if the appropriate frequency and adequate power values are applied. Because the therapeutic temperature is close to the complication limit, the practitioner should be an expert using the device, well-knowledgeable about the regional skin structure and thickness, as well as be able to properly adjust the application doses in order to get therapeutic results.