The door system of the present invention includes a mounting frame assembly and a tilt-up door pivotally and slidably mounted within the mounting frame assembly. The door system is installed in a door rough opening as an integral unit, simplifying installation. At least one hydraulic cylinder is utilized to actuate the door between its open and closed positions. A stabilizer including a door component secured to the tilt-up door and a door component secured to the frame assembly are used to stabilize the door when it is in its open position.