Objective To discuss relationships of brain-derived neurotrophic factor (BDNF) and its Val66Met gene polymorphism with chronic tinnitus, and determine the correlations between the therapeutic effect and severity of tinnitus and serum BNDF concentration.Methods Serum levels of BDNF and its rs 6265Val66Met gene polymorphism were measured in 30 patients with tinnitus (study group) and 30 healthy controls (control group). The severity of tinnitus was assessed using the tinnitus handicap inventory (THI). All the tinnitus patients were divided into two groups according to the THI score: mild group (THI≤36 score) and moderate to severe group (THI≥38 score). All patients were treated with transcranial magnetic stimulation. The changes of THI score and serum BDNF level before and after treatment in the study group were observed to determine the correlations between the therapeutic effect and severity of tinnitus and serum BNDF concentration.Results The serum BDNF concentration in the study group was lower than that in the control group (P<0.05). The serum BDNF concentration after treatment was higher than that before treatment in the tinnitus patients who had responded to treatment (P<0.05), while the serum BDNF concentration did not change significantly in the tinnitus patients who had not responded to treatment. In both the study group and the control group, there was no significant correlation between the gene polymorphism of BDNF (rs 6265Val66Met) and the serum BDNF concentration.Conclusion The serum concentration of BDNF is correlated with the prognosis of tinnitus, and BDNF may be involved in the occurrence of tinnitus through the mechanism of neuroplasticity. Therefore, it is speculated that serum BDNF concentration may be used as one of the objective indicators of therapeutic effect in tinnitus.