Abstract: A human sensing pet deterrent system for protecting a specific indoor area is disclosed. The human sensing pet deterrent system includes an ultrasonic detection system that determines whether a human or a pet is entering the protected area, a motorized fluid sprayer system in the proximity of the protected area, and a microcontroller which controls and provides communication between the systems. The fluid sprayer system delivers a spray or mist stimulus for a preset duration which discourages a pet from entering the protected area. If the ultrasonic detection system detects a human, the fluid spray system is deactivated for a preset duration, thereby enabling the human to enter the protected area.