Abstract: An apparatus for detecting tampering with a container sealed with a cap. The apparatus is comprised of a radio frequency transceiver for transmitting a signal upon receipt of a transmit command and an antenna attached thereto. In a first embodiment, the radio frequency transceiver and the antenna are mounted on a substrate attached to the container and the cap. The radio frequency transceiver is disabled when the antenna is separated into two portions upon breaking the seal between the container and the cap. In a second embodiment, the apparatus is mounted within a cap and is also comprised of a logic circuit and a probe that detects changes in the level of contents within the container. The probe produces an output relative to the level of contents in the container. The logic circuit then either prevents the radio frequency transceiver from communicating or causes it to transmit an alternative signal.