In this paper, a computer controlled cold-hot therapy device with thermoelectric module has been designed. This device is used in order to balance temperature of body in case of injury, fever etc. In this medical device, cold and hot therapy operations have been accomplished by changing the feeding voltage and feeding polarity of thermoelectric modules. Temperature was measured via PIC18F4550 microcontrollers and USB port and AD595AQ Monolithic Thermocouple Amplifiers were used for transferring data of K type temperature sensors to microprocessor. A control interface has been developed in VisualBASIC6.0 to monitor and record the temperature data, and control the device by the computer. All tests were conducted at variable temperature inside a heated chamber to simulate the human body temperature. The computer controlled cold-hot therapy device with thermoelectric module was operated and tested at variable water flow rates and variable voltages by computerized control. As a result of this study, cold and hot therapy operations have been realized via this medical device. Cold therapy with splint is a vital first aid application in Traffic, sports, work accidents etc. According to the literature, cold and hot therapy temperatures range from 0 degrees C to 15 degrees C and from 40 degrees C to 45 degrees C respectively. The study was performed at the simulated body temperature of 37 degrees C. The hot and cold therapy device which was designed was tested at various power values obtained cold surface temperatures from -3.4 degrees C to 5.5 degrees C and hot surface temperatures from 37.8 degrees C to 58.3 degrees C.