The results of this study showed that pain decreased following application of stabilization and Mckenzie exercises. Disability decreased only after the application of stabilization exercises. The results indicated that the effect of stabilization exercises on pain and disability was greater than Mckenzie exercises in chronic low back pain. Also, stabilization exercises were effective in increasing the resting thickness of the left Transverse abdominis muscle, the thickness of the right Transverse abdominis muscle during ADIM, the thickness of the left Transverse abdominis muscle during active SLR, thickness of the left multifidus muscle when contracted. Comparison of the effects between the two methods of exercises on muscle thickness showed that stabilization exercises were more effective than Mckenzie exercises in increasing the thickness of the right Transverse abdominis muscle during ADIM, and the thickness of left Transverse abdominis muscle during ASLR.