Abstract: This invention relates to a system for the power-assisted opening of parasols, umbrellas and the like comprising a shaft of which one of the ends is provided with a cap on which ribs are articulated in star-like manner, wherein at least one compressed air jack is articulated by its cylinder on a ring fixed to the shaft, while the free end of its piston rod is pivotally mounted with respect to a tab of the rib lying in the same vertical plane as the jack. In folded position, the point of pivoting of the end of the piston rod with respect to the tab lies between the shaft and a line joining the axis of articulation of said jack on the ring and the point of articulation of the rib in question on the cap with a view to constituting a toggle joint maintaining the parasol closed.