Abstract Objective: To determine whether Betahistine dihydrochloride is effective in treating primary tinnitus in adults. Design: Intention-to-treat, randomized, triple-blinding, monocentric clinical trial Setting: Botucatu Medical School – State University of São Paulo (Unesp) in Brazil. Participants: 62 adults with primary tinnitus for at least six months (both sexes), and a Tinnitus Handicap Inventory score above 18 were randomized in two equal study groups: betahistine (24 mg of oral betahistine 12/12hs for 90 days), control group (a matched placebo). Main outcomes measures: Primary outcome measure - change in Tinnitus Handicap Inventory score; secondary outcome - Clinical Global Impression Improvement and participants’ perceived improvement after the intervention. Results: Participants had a median age (interquartile range) of 54 (48 to 60) years, with a balanced number of men and women. There was no significant difference in Tinnitus Handicap Inventory change before and after treatment between the study group and control (median difference of -2 points; 95% CI, -8 to 6 points); the Tinnitus Handicap Inventory after intervention was a median (interquartile range) of 4 (-4 to 14) lower in the betahistine group, and a median (interquartile range) of 2 (-6 to 10) lower in the placebo group. The secondary endpoint, covariate adjustment, and per-protocol analysis provided similar results, and side effects were without difference between both groups. Conclusion: Betahistine was ineffective when compared to the placebo in the treatment of the primary tinnitus .