A roller blind system for a vehicle for shading a rear window, having a fabric sheet movable between stowed and functioning conditions, with a pull-out profile provided at a distal end thereof and two guide rails located on sides of the sheet, whereby the pull-out profile incorporates two sliding pieces at its opposite ends each engaged with one guide rail. The pull-out profile covers an outlet slot for the sheet. The pull-out profile has a variable length and includes a main segment bonded to the sheet and two movable end segments movable relative to the main segment by a guide. The covering face includes a main section on the main segment and side sections on the end segments. The side sections enter into a receiving pocket enclosed by the main segment when the length of the pull-out profile is reduced.