Background The international prevalence of adult attention deficit hyperactivity disorder (ADHD) is estimated at 2.5%. ADHD is associated with serious impairment in academic, occupational, social and emotional functioning. Despite the debilitating nature of this disorder, few individuals with ADHD receive appropriate help. Further, although psychopharmacology is considered the first-line treatment of adults with ADHD, it is now recognized that medication alone may be insufficient. Thus, cognitive behavioral therapy (CBT) is a promising approach.Objectives This study aimed to review literature and investigate the efficacy of CBT, in reducing ADHD symptoms and comorbid conditions such anxiety and depression for adults with ADHD, by several studies through a meta-analysis.Methods We searched the literature from 1946 through 2015 using especially MEDLINE, EMBASE and PsycINFO. We used a random-effects model, Odds Ratios (OR) and Hedge's g.Results Data from 12 randomized controlled studies were included, totaling 575 subjects. The results showed a significant reduction in ADHD symptoms (Hedge's g = 0.95) and comorbid anxiety (Hedge's g = 0.39) and depression (Hedge's g = 0.30) for the CBT group in comparison with controls. Following the end of treatment, ADHD symptoms continue to improve, but not the comorbid conditions.Conclusion In summary, in adults with ADHD, CBT appears to be a promising treatment.