Abstract: A roll-up screen door includes a long, narrow housing having a length adapted to extend vertically for the full height of a door casement opening. The housing contains a conventional spring-biased roll upon which is initially wound a large sheet of flexible screen material, one end of which is secured to the roll so that the screen material can be unwound from the roll against the tension of the roll. When the housing is mounted adjacent to one side of the vertical trim strip along one side of the door casement opening, the screen material passes through a longitudinal exit slot in the housing in a plane located inwardly of the front face of the vertical trim strip, so that the screen material sealingly engages the adjacent vertical trim strip when it is stretched across the door opening.