We have developed a wide area intruder detection surveillance system which was delivered to the Japanese market last summer. This technology is known as MELWATCH which stands for MELco WATCH(to keep lookout). It has been installed at several sites in Japan. MELWATCH is composed of a pair of sensor cables, a sensor unit and an intrusion detection terminal. The sensor cables are composed of a transmission and a receiving cable (transceiver cables), both of which are off-the-shelf leaky coaxial cables. The sensor cables are deployed in parallel along the boundary to be monitored. Upon activation, the sensor unit sends an electric wave into the transmission cable which results in the electric wave leaks from the cable. The receiving cable receives the leaked electric wave and an electric field is formed between the cables. When an intruder enters the electric field, the sensor unit detects this activity and the precise location of the intrusion. Moreover, this sensor is less affected by the environmental noise, such as trees or small animals, nor weather conditions. In addition, the ability to specify the intrusion point makes it possible to configure the more sophisticated system with pan-tilt-zoom cameras. In this paper, we show the effectiveness of MELWATCH through the field data of the several installed sites.