Objectives: To compare the efficacy of two types specific exercise intervention (deep and superficial abdominal muscle exercises) in the treatment of patients with chronic low back pain (CLBP). Design: A randomized, comparative, repeated-measures. Subjects: Twenty-four patients with CLBP (at least for 3 months), mean $age{pm}SD=51.58{pm}16.21$ (yrs). Methods: Twenty-four patients with this condition were assigned randomly to two treatment groups. Both first and second group underwent 3 weeks specific exercise treatment program. The first group specific trained for the deep abdominal muscles. The second group specific trained for the superficial abdominal muscles. Results: After intervention, the first group showed a statistically significant reduction in pain intensity and functional disability levels (p<.05). The second group showed no significant change in these parameters after intervention (p>.05). Conclusions: According to results, a "deep abdominal muscle exercises" treatment approach appears more effective than a "superficial abdominal muscle exercises" treatment in patients with CLBP.