Sentry Gun with face detection is a turret based weapon system, that can neutralize targets with user control, within its range. This model consists of mount with two servo motors for tilt and pan, a target detector (a camera) and an airsoft-gun. There are many ways to use a real sentry gun: anti-air defense, anti-vehicle defense (at checkpoints) and anti-personnel defense. This system falls under the third category. This device has an automatic toy gun mounted on top of a mechanical assembly as a weapon which is triggered by an electronic relay. The gun will have the ability to move in the theta and pi directions (i.e. pan and tilt), which will be controlled by two servo motors connected to Arduino Duemilanove board. The camera is mounted on a gun and is used to get the real time image and it will transfer it to a computer where an image processing algorithm calculates the position of target. This calculation is then sent to the Arduino board and then the motors orient the gun at appropriate coordinates. Once the gun is pointed towards the target, it is locked on it. The trigger mechanism is controlled manually by a user sitting at the backhand.