A modular radio-identification system including a first passive radio-identification module having a housing with a memory for storing an identification datum disposed inside the housing and being linked to an antenna. The system also includes a second active radio-identification module having a housing with a controller disposed therein, the controller being linked to a supply battery, to a transmiter/receiver and to at least one sensor. The housings of the two modules are equipped with components of reversible and complementary fixing which are adapted for co-operating together so as to allow the reversible fixing of the second module on the first module. The modules include electrical connection components adapted for establishing an electrical connection between the memory and the controller once the second module is fixed on the first module. The system may be supplemented with a hood for covering the first module.