Aims: To explore the effect of baclofen in a dose of 20 mg three times per day, compared with the already studied dose of 10 mg three times per day, in the treatment of alcohol dependence. Methods: We present a secondary analysis of a 12-week double-blind, placebo-controlled, randomized clinical trial with two doses of baclofen, specifically 10 mg t.i.d. and 20 mg t.i.d. Out of 94 subjects consecutively screened, 42 were randomized into the study. Fourteen of the 42 patients were randomly allocated to placebo, 14 to the group treated with baclofen 10 mg t.i.d. (B10 mg) and 14 to the group treated with baclofen 20 mg t.i.d. (B20 mg). Results: Compared with patients allocated to placebo, patients allocated to the B10 mg group had a 53% reduction in the number of drinks per day (P < 0.0001) and patients allocated to the B20 mg group had a 68% reduction in the number of drinks per day (P < 0.0001), with respect to the number of drinks per day during the 28 days before randomization. The effect of baclofen 20 mg t.i.d. was greater than that of baclofen 10 mg t.i.d. (P = 0.0214, Wald test) showing a dose–effect relationship. Both doses of baclofen were well tolerated. Conclusion: This is provisional evidence of a dose–response effect for baclofen in the treatment of alcohol dependence.