A methodology for the design of frequency and environment “robust” UHF RFID Tags is proposed and applied for the automatic generation of tag antennas. This is an automated process of antenna generation mainly associated with a Genetic Algorithm optimizer. Original antenna topologies are generated and selected automatically according to an evolutionary algorithm. The efficiency property is implemented as a set of constraints and integrated in the cost functions of the design process. Moreover, the proposed methodology is fully automatic and avoids classical tedious simulation steps. The methodology is applied to design “robust” RFID tags, under constraints of size, UHF frequency bands and environment characteristics. The design of efficient tags showing good performance for the worldwide UHF band is demonstrated. Some designs have been realized and measured in an anechoic chamber owing to an experimental set up dedicated to RFID communication characterization. Good agreement between simulation and measurement is observed.