Abstract: The invention refers to an electronic system for defence against fires in forest areas and more generally for monitoring the territory. The system comprises a network of alarm stations (SA) distributed over the territory being controlled, where each alarm station (SA) is enclosed in an air-scaled mechanically-sealed protective casing and comprises at least one sensor (S1-S3), a microcontroller (MC), a transceiver (RTX) at low power radiofrequency fitted with antenna (A) and a battery (B) for the electric powering of said sensor (S1-S3), said microcontroller (MC) and said transceiver (RTX). The alarm station network (SA) is in wireless communication with at least one intermediate detection unit (CIR) in turn in communication with at least one central control station (SC) controlled by bodies authorised to control and defend the territory.