Many treatments for chronic tinnitus have been attempted, but the condition remains difficult to cure, especially in the case of cochlear tinnitus. We conducted a prospective, double-blind, placebo-controlled study to assess the effect of low-dose laser therapy on chronic cochlear tinnitus. Our study population was made up of 66 patients-33 who received active laser treatment (case group) and 33 who received inactive dummy treatment (control group). Patients in the laser group received 5 mV with a wavelength of 650 nm for 20 minutes a day, 5 days a week, for 4 weeks. The controls followed the same schedule, but they were "treated" with an inactive device. The degree of tinnitus was evaluated before and after treatment in each group in three ways: (1) the Tinnitus Severity Index (TSI), (2) a subjective 10-point self-assessment scale for tinnitus loudness, and (3) the Tinnitus Evaluation Test (TET). At study's end, we found no statistically significant differences between the case and control groups in the number of patients who experienced a reduction in TSI values (p = 0.589) or a reduction in subjective self-assessment scores (p = 0.475). Nor did we find any significant reductions in the loudness (p = 0.665) and frequency (p = 0.396) of tinnitus as determined by the TET. We conclude that 5-mV laser therapy with a wavelength of 650 nm is no better than placebo for improving hearing thresholds overall or for treating tinnitus with regard to age, sex, environmental noise level, and the duration of tinnitus.