Abstract: A device to detect the position of the toilet seat and alert the user by means of a visual signal. It consists of housing mounted on the underside of a toilet seat cover (3). The housing encloses a light source (4), the circuit (5) and power source (11) required to energize the source and a mechanically operated sensor device (7), which detects the position of the seat If the seat is up, the sensor device detects the position of the seat whereby sending the appropriate signal through the electronic circuitry to gently illuminate the seat cover with the light source (FIG. 2). The device has the built-in feature, which prevents it to activate the light source when both seat and cover are in horizontal down position, thereby conserving the power in the batteries which are used as the power source (FIG. 3).