The level of security in any organization/establishment determines its growth and productivity. This project ""3-Stage Intruder Radio Alert System"" seeks to eliminate the high level of unreliability usually encountered with human security systems. The design incorporates two modules: The transmitter and the receiver module. The intruder detection actually takes place at the transmitter module in three stages using photo sensors mounted at strategic points within the premises of intrusion. The first and second stages produce audio and visual alerts respectively whereas at the third stage, the signal from the third sensor is built-up, amplified and transmitted over a distance to a remote receiver to trigger both audio and visual alerts simultaneously. The design comprises group circuits such as power supply unit, modulators and demodulator, and discrete component such as photo sensors, resistors, SCRs, diodes, capacitors, inductors and comparator (Operational Amplifier).