The purpose of this research is to investigate the impact of speech therapy with Cognitive Behavior Therapy (CBT) on reducing the severity of stuttering & anxiety for adults who stutter in the city of Isfahan, Iran. The study used a semi-experimental design with pre-test/post-test control groups and it was conducted among 24 clients. The sample was selected through available sampling method among the clients suffering from stuttering and attended public speech therapy clinics of Isfahan. The measurement instruments were Stuttering Severity Instrument (SSI4) and Beck & apos; s Anxiety Inventory (BAI). After doing the pretest, clients were placed into one experimental group of speech therapy with CBT and one control group. Speech therapy for this research included ten 45-minutes sessions accomplished for each individual subject and CBT included ten 90-minutes group sessions. After finishing the therapy sessions, the posttest was executed on both groups. For statistical analysis of data, Analysis of Covariance was carried out. The research findings indicated that speech therapy with CBT reduced the severity of Stuttering and Anxiety. Speech therapy with CBT is effective in reducing Stuttering & Anxiety.