A rollover protection system for motor vehicles with - a base body arrangeable in a fixed manner to the vehicle, - a rollover body adjustable with respect to the base body between a storage position and a rollover position, - a drive unit pretensioning the rollover body in the direction of the rollover position and - a locking unit locking the rollover body in the storage position with - a locking element pretensioned in the direction towards a locking rail arranged on the rollover body, which is arranged in an adjustable manner on a locking element carrier between a locking position locking the rollover body and an unlocking position releasing the rollover body, characterized in that - a blocking element adjustable between a blocking position immobilizing the locking element in the locking position and an opening position releasing the locking element as well as - an actuating element adjustable manually between an operating position and an engaging position for displacing the locking element out of the locking position into the unlocking position are arranged on the locking unit, - wherein the actuating element is connected with the blocking element such that a manual adjustment of the actuating element from the operating position into the engaging position causes a displacement of the blocking element out of the blocking position into the opening position and wherein a driving device is arranged on the blocking element for displacing the blocking element from the blocking position into the opening position. - a base body arrangeable in a fixed manner to the vehicle, - a rollover body adjustable with respect to the base body between a storage position and a rollover position, - a drive unit pretensioning the rollover body in the direction of the rollover position and - a locking unit locking the rollover body in the storage position with - a locking element pretensioned in the direction towards a locking rail arranged on the rollover body, which is arranged in an adjustable manner on a locking element carrier between a locking position locking the rollover body and an unlocking position releasing the rollover body, - a locking element pretensioned in the direction towards a locking rail arranged on the rollover body, which is arranged in an adjustable manner on a locking element carrier between a locking position locking the rollover body and an unlocking position releasing the rollover body, - a blocking element adjustable between a blocking position immobilizing the locking element in the locking position and an opening position releasing the locking element as well as - an actuating element adjustable manually between an operating position and an engaging position for displacing the locking element out of the locking position into the unlocking position - wherein the actuating element is connected with the blocking element such that a manual adjustment of the actuating element from the operating position into the engaging position causes a displacement of the blocking element out of the blocking position into the opening position and wherein a driving device is arranged on the blocking element for displacing the blocking element from the blocking position into the opening position.