In the search for new psychopharmacologic options in the treatment of obsessive-compulsive disorders (OCD), some findings suggested that augmentation with buprenorphine, a partial-opioid agonist used to treat opioid addiction, moderate acute pain and moderate chronic pain, is worthy of consideration. Accordingly, to explore this possibility further, a double-blinded, placebo-controlled clinical trial was performed.A total of 43 patients (mean age: 34.41 years; SD = 6.58; 53.5% males) with refractory OCD and treated with SSRIs or clomipramine at therapeutic dosages were randomly assigned either to an adjuvant buprenorphine or to an adjuvant placebo condition. Patients completed the Yale-Brown-Obsessive-Compulsive Scale (Y-BOCS) at baseline, weeks 3, 9 and 12 (study completion). Buprenorphine (2–4 mg; sublingual) and placebo (tablets with identical shape, color, consistency, and scent) were given daily.Symptoms of obsessive-compulsive disorders decreased over time, but more so in the buprenorphine than in the placebo condition. Substantial improvements were observed up to week 3 and then 9. Response and partial response were observed in the buprenorphine at week 9 more than in the placebo condition. The advantage had disappeared by week 12.The pattern of results suggests that adjuvant buprenorphine augmentation can reduce symptoms of obsessive-compulsive disorders after only three weeks, compared to a placebo. Adjuvant buprenorphine seems to accelerate symptom improvement.