Abstract: An orthosis (10) for supporting an arm of a person and a method for the placement of an orthosis are provided. The orthosis includes a securing device (11) for securing the orthosis to a torso of the person, and a positioning device (12) for supporting and fixing the forearm, elbow and/or upper arm, relative to a person's shoulder associated to that arm. The positioning device is supported by the securing device. The securing device includes an abdominal strap device (13) and a shoulder strap device (14). The abdominal strap device surrounds the torso in a transversal plane, and the shoulder strap device runs over a person's shoulder opposite of that arm. The shoulder strap device includes a shoulder strap (23) and a connected chest strap (22). The straps are hinged to ends (24, 29) of the positioning device and to a ventral portion (26) of the abdominal strap device.