Abstract: A system for sensing and repelling an animal is disclosed. The system contains an infrared motion detector which detects any warm moving object. Once detection has occurred, a Radio Frequency (R.F.) pulse signal is transmitted by a radio transmitter/receiver to the involved area. If an animal such as a family pet is wearing a collar which contains a radio receiver/transmitter, the R.F. pulse signal is received by the receiver/transmitter in the collar and an R.F. pulse response signal is transmitted which is received by the transmitter/receiver in the system. If a signal is received, the repelling subsystems which is a flood light and a water spray is deactivated. If a signal is not received, the repelling subsystems are activated to scare the unwanted animal away. The system can also be used for sensing the presence of an animal since the R.F. unit is detachable and can be used as a stand alone unit.