Objective: To evaluate the efficacy of Ginkgo biloba as a complementary therapy for attention-deficit/hyperactivity disorder (ADHD). Methods: Children and adolescents with ADHD received methylphenidate (20-30mg/day) plus either G.biloba (80-120mg/day) or placebo for 6 weeks. Parent and teacher forms of the ADHD Rating Scale-IV (ADHD-RS-IV) were completed at baseline, week 2, and week 6. Treatment response was defined as 27% improvement from baseline in the ADHD-RS-IV. Results: Compared with placebo, more reduction was observed with G.biloba regarding ADHD-RS-IV parent rating inattention score (-7.74±1.94 vs.-5.34±1.85, P<0.001) and total score (-13.1±3.36 vs.-10.2±3.01, P=0.001) as well as teacher rating inattention score (-7.29±1.90 vs.-5.96±1.52, P=0.004). Response rate was higher with G.biloba compared with placebo based on parent rating (93.5% vs. 58.6%, P=0.002). Conclusions: The G.biloba is an effective complementary treatment for ADHD. Further studies with longer treatment duration are warranted in this regard. IRCT2014111519958N1. © 2015 Elsevier Ltd.