Robotic exoskeletons have drawn much attention recently due to their potential ability to help the stroke and spinal cord injury patients to regain the ability of walking. However, the biggest challenge is the balancing of the exoskeleton and how it can balance is still an open question. Most of the time, patients using such exoskeleton devices require sufficient upper body strength to control upright posture and also manipulate crutches/walking frames to partially support body weight and keep balance. However, high energy cost and the high potential of falling using these devices remains a problem. In this paper, the issues are tackled by virtue of a proposed balance stabilizer mechanism which is able to provide active balance assistance for robotic exoskeletons. The design of a robotic exoskeleton together with balance stabilizer mechanism will be presented and discussed. In addition, a trajectory generation method, which can generate dynamically stable and tunable gait pattern, will also be shown. Finally, clinical trial results with a tetraplegia subject is presented and discussed.