A method for monitoring objects, the objects including, respectively, tags that backscatter ambient signals. The method is implemented by a receiver device and includes: receiving a first backscattered signal originating from a first object, the first backscattered signal corresponding to an ambient signal and including a message having an identification datum relating to the first object; and determining the desired presence or the undesired presence of the first object in a geographical area as a function of the identification datum relating to the first object. Use for systems for monitoring objects, for example to detect proximity between objects that should not be close to one another.