A door assembly for pivotally securing a door to an animal enclosure or other enclosure. The door assembly comprises a pivot pin assembly integrally formed with the door and a hinge secured to the enclosure adjacent the opening. The pivot pin assembly preferably comprises a vertically oriented pivot pin integrally formed with upper and lower horizontal support members extending from upper and lower ends of the pivot pin across a portion of the door. The pivot pin is fitted within a hinge barrel formed within the hinge in a manner to permit the pivot pin to rotate within the barrel such that the door may be pivoted from an open to a closed position.