Rasagiline is a monoamine oxidase B inhibitor with demonstrated efficacy and safety in patients with Parkinson’s disease (PD). We recently conducted the first randomized, double-blind, placebo-controlled trial of rasagiline in Japanese patients with early PD and now report the results of its open-label extension (clinicaltrials.gov, NCT02337751). In the double-blind trial, patients aged 30–79 years with PD diagnosis within 5 years and Movement Disorder Society-Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Part II + Part III total score ≥ 14 were randomized to placebo or rasagiline 1 mg/day for 26 weeks. Of 210 patients who completed the randomized trial, 198 (95 placebo, 103 rasagiline) entered the extension and received rasagiline 1 mg/day for 26 weeks. Analyses included patients who received rasagiline anytime during double-blind and/or extension periods; mean (standard deviation) treatment duration was 169.6 (39.57) and 316.5 (88.89) days in placebo–rasagiline (
n
= 95) and rasagiline–rasagiline (
n
= 117) groups, respectively. The incidence of treatment-emergent adverse events (TEAEs; primary outcome) was 53.7% and 77.8% in the placebo–rasagiline and rasagiline–rasagiline groups, respectively. Drug-related TEAEs occurred in 24.2% and 49.6% of patients and serious TEAEs occurred in four (two drug related) and six (one drug related) patients in the placebo–rasagiline and rasagiline–rasagiline groups, respectively. The mean change in MDS-UPDRS Part II + III total score from baseline (before rasagiline) was − 2.8 points in both the placebo–rasagiline (mean [95% confidence interval] − 2.8 [− 4.05, − 1.59]) and rasagiline–rasagiline (− 2.8 [− 4.57, − 1.01]) groups. In conclusion, up to 52 weeks, rasagiline was well tolerated with sustained motor symptom improvement, supporting its use in Japanese patients with early PD.