Abstract: A clean room covering or enclosure for a portable computer, wherein the computer has a keyboard portion and a screen portion connected by a hinge foldable between closed and open positions. The enclosure comprises a flexible sleeve for receiving the keyboard portion of the portable computer, with the sleeve having an opening through which the keyboard portion is inserted and removed, a transparent portion for viewing and operating the keyboard and a gas permeable vent portion adapted to restrict flow of contaminant particles. A flexible flap extends from the sleeve portion and is adapted to wrap around and over the screen portion of the portable computer, and has a transparent portion for viewing the screen. The enclosure also includes a reclosable seal for securing the flexible flap around the screen portion. The reclosable seal preferably secures the flexible sleeve opening to restrict flow of contaminant particles.