During my thesis I created a working ECG measuring system with a given specific integrated circuit and a user interface which consists of an Android application. I present the background and the development of this measuring system. To reach the goal it was necessary to acquire the background knowledge of the physiology, to design and create the hardware of the external unit, to become familiar with the various signal processing algorithms, to program them and to create a graphical user interface. Moreover, I had to make two different softwares in three different programing languages. I implemented the Android software in Java, the software of the external measuring unit in C and Assembly languages. In this system a detector of R wave was implemented with this the application can show the heart rate. To the end of my thesis work the measuring system had been developed, that can perform basic measurements, but it needs further important development from the perspective of both aesthetic and functionality to become practical and vendible product.