INTRODUCTION: Treatment of individuals who have committed sexual offences with Testosterone-Lowering Medication (TLM) is a comparatively intrusive kind of intervention, which regularly takes place in coercive contexts. Thus, the question of efficacy, but also the question of who should be treated, when and for how long, are of great importance. METHODS: Recidivism rates of TLM-treated high-risk individuals (+TLM;  = 54) were compared with high-risk individuals treated with psychotherapy only in the same forensic outpatient clinic (-TLM;  = 79). RESULTS: Group differences suggested a higher initial risk of + TLM (e.g. higher ris-assessment, previous convictions). Despite the increased risk, after an average time at risk of six years, +TLM recidivated significantly less often and significantly later than - TLM (27.8% vs. 51.9%). Such an effect was also found for violent (1.9% vs. 15.2%), but not for sexual (5.6% vs. 10.1%) and serious recidivism (5.6% vs. 10.1%), which could be explained partly by the small number of cases. In the course of treatment, TLM proved to be a significant variable for a positive process, whereas a high risk-assessment score indicated a rather negative course. In total,  = 19 individuals had stopped their TLM treatment, of these 31.6% recidivated. CONCLUSION: The results support the efficacy of TLM, particularly in the group of high-risk offenders.