Medical treatment of levodopa-induced dyskinesia (LID) in Parkinson’s disease (PD) is an unmet need. ADS-5102 (amantadine) extended-release capsules is being developed for the treatment of LID in patients with PD. Evaluate the long-term safety and tolerability of 274 mg ADS-5102 for LID in PD. In an ongoing, open-label safety study (NCT02202551), PD patients with LID received 274 mg of ADS-5102 once daily at bedtime. Patients were recruited from previous ADS-5102 trials. In addition, patients were enrolled who were ineligible for previous ADS-5102 trials due to previous implantation of deep-brain stimulation (DBS) devices. The primary outcome measure was safety assessed through adverse events (AEs). Efficacy was assessed using the Movement Disorder Society–Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), Part IV and its subparts. For this interim analysis, 223 patients received ADS-5102 for a mean duration of 348 (SD 182) days. The most common AEs included falls (25.1%), visual hallucinations (19.3%), peripheral edema (13.0%), and constipation (12.6%). Overall, 32 patients (14.3%) discontinued due to an AE. In patients receiving placebo in previous studies, the mean MDSUPDRS, Part IV scores decreased by 3.4 points from baseline (n= 78) to week 8 and remained stable through week 64 (n= 21). In patients receiving ADS-5102 in previous studies, the mean baseline (n= 61) MDS-UPDRS, Part IV score was low due to the response to ADS-5102 in previous studies and remained stable through week 64 (total of 88 weeks; n= 21). The effect was primarily due to reduction in item 4.2 (functional impact of dyskinesia) and item 4.4 (functional impact of motor fluctuations).