Objective To explore the efficacy and safety of low frequency repetitive transcranial magnetic stimulation(rTMS) for adolescent patients with first-episode depression. Methods Totals of 30 adolescent first-episode depression patients with no medication were randomly divided into rTMS group (15 cases) and control group (15 cases). Low frequency rTMS located on right dorsolateral prefrontal cortex (DLPFC)was used in rTMS group for 2 weeks (5 times per week)， compared with sham stimulation in control group. No drug was used during treatment. The efficacy was assessed by Hamilton Depression Scale (HAMD24). Results (1) There was significant difference between two groups on effective rate(100% vs 0%， P＜ 0.01). (2)There was significant reduction both in HAMD24 total scores and in sub-scale factors’ scores in rTMS group after treatment（ P＜0.05）. But there was no significant differences in control group (P ＞ 0.05). (3) No significant difference was found in incidence of adverse reaction between two groups (P＞ 0.05). Conclusions Low frequency rTMS can effectively and safely improve adolescent patients with first-episode depression.