Abstract: A rolling reef system for the main sail (4) of a sailing vessel, the said main sail having an after leech (5), an under leech (7) secured to the boom (3) and a fore leech (6) connected to the mast (2), wherein said boom can be mounted on the mast in such a manner that it is both rotatable along its longitudinal axis and can be swivelled about the mast. The main sail is provided with one or more battens (11, 12) extending practically parallel to the under leech (7) from the after leech up to the fore leech (6). At the end of the boom (3) that is adjacent to the mast, the boom is provided with a disc (9) extending coaxially to the boom and having a significant larger diameter than the boom itself. The fore leech of the main sail comprises a rope (13) having a relatively small guiding profile, said rope is slidably accommodated by and retained in a guiding profile (14) secured to the mast, the said profile extending over practically the entire height of the main sail.