The present invention relates to a brake system in a wheeled zimmer frame with two zimmer frame legs which have two telescopically adjustable frame tubes (10, 11, 20, 21, 30, 31, 40, 41), of which the one supports in its upper region a handle (12, 412) and a brake lever (13, 413) and of which the other is provided in its lower region with a brake device (18, 420) for braking a wheel (19), the brake system including a telescopically adjustable brake rod (17, 217, 317, 47) which is disposed within the frame tubes between the brake lever and the brake device, and is provided with two parallel rods (17a, 17b; 217a, 217b; 317a, 317b; 47a, 47b) of which the one is interconnected with the brake lever (13, 413) and the other is interconnected with the brake device (18, 420) and an axial longitudinal adjustment of the frame tubes to the desired vertical position on the handle synchronously entailing a corresponding alteration of the length of the brake rod, and at least one device (110-112; 113-115; 211, 216; 311; 316) for locking the frame tubes and the rods (17a, 17b; 217a, 217b; 317a, 317b; 47a, 47b) of the brake rods (17, 217, 317, 47).