This paper presents the design and fabrication of a broadband UHF RFID tag for bio-monitoring applications. The proposed tag is realized with a thin FR4 substrate of 200 µm, which can be considered as flexible. It shows good performances both in free space and placed on human body. For instance, in free space, the tag can be read at 14 m in the UHF RFID band and at an average distance of 4.6 m when it is placed on the human body. The overall tag size is only 80 mm × 50 mm × 200 µm.