The aim of my project is to implement a micro-controller based alarm system. In the paper, alarm systems and their elements are described. The necessary elements were selected and used, during the implementation of the system. The project consisted of the use of schematic diagrams to describe the circuit in graphical form and the use of ATmega128 micro-controller as the main center for the hardware assembling of selected components. Also, a control program was developed for above-mentioned alarm system.