Anxiety disorders are one of the most common disorders and are characterized by a maladaptive and exaggeratedly anxious response to some stimulus. The CBT treatment for anxiety disorders suggests cognitive techniques of restructuring and cognitive flexibilization and behavioral techniques such as exposure, systematic desensitization and body relaxation techniques. An investigation was conducted through three case studies. Relaxation techniques were applied to all three patients, including progressive relaxation, passive relaxation and diaphragmatic breathing. To analyze the efficacy of relaxation techniques the patients were asked to indicate their anxiety in a scale from zero to ten (zero is no anxiety and ten is high anxiety) before and after the techniques. Relaxation techniques have been successful in the three cases of this study and achieved the goal of decreasing anxiety, but it should be emphasized that the use of these techniques is not universal and depends on each patient. Keywords: Cognitive Therapy, anxiety, relaxation.