OBJECTIVES: For Parkinson’s disease (PD), several epidemiological studies have been carried out across Japan. However, pharmacological management of PD has not been extensively investigated, especially alignment with guideline (different first line treatment recommendation depends on patients with/without dementia). We studied the situation of prescriptions for PD using Real World Data. METHODS: The JMDC (Japan Medical Data Center) claims data of approximately 2.5 million insured people between January 2005 and August 2015 was used for data collection. Inclusion criteria for analysis were patients with diagnosis of PD [defined by ICD-10 (G20-G22) ] and at least one prescription of L-dopa or dopamine agonists (DA).  The frequency of prescribed medicines was estimated for patients newly diagnosed with PD for the entire period of this data collection. Subgroup analysis by presence of dementia [defined by ICD-10 (F00-F04)] was also conducted. RESULTS: A total of 3,069 patients were identified including 1,349 new patients. The most frequently prescribed medicines during the entire study period were DA (30.0 %) and L-dopa (28.6 %). As first line treatment, L-dopa was prescribed 41.2 % of the time and DA was prescribed 39.9% of the time. Selegiline (MAO-B inhibitor) was less frequently prescribed (0.8 %). In subgroup analysis, L-dopa was prescribed more among patients with dementia (62.2 %) than those without dementia (40.0 %). In contrast, DA was prescribed more among patients without dementia (41.1 %) than those with dementia (18.9 %). CONCLUSIONS: This study confirmed that both L-dopa and DA were the main first line treatments for PD, and L-dopa was slightly preferred. Also, it was found that L-dopa was prescribed more for patients with dementia, and DA was contrary. This treatment pattern was reflective of the Japanese PD treatment guideline. Further studies are needed to understand more details of prescribing pattern.