OBJECTIVES: Clinical trial simulation (CTS) is encouraged to prevent clinical trials (CT) from failing. Healthcare database (HDB) is a potential source for baseline characteristics in CTS. The study evaluates, 1) overlapping between distribution of baseline characteristics extracted from Japanese HDB and also from two Japanese CTs for dyslipidaemia drugs, and 2) applicability of HDB as a sampling frame (SF) for baseline data in CTS for dyslipidaemia drug development. METHODS: We extracted data from MinaCare HDB which contains both insurance claims and health check-ups of people insured by  employment-based insurances as of April 2013 and built two SFs according to eligibility criteria of the protocol in two CTs (Protocol-A and Protocol-B) conducted by Pfizer Japan Inc.. Distribution of patient characteristics at screening, such as body mass index (BMI) and low density lipoprotein cholesterol (LDL-C) levels, were compared between SFs (n=1663 for Protocol-A, n=5011 for Protocol-B) from MinaCare HDB and CTs, for Protocol-A  (n=165) and Protocol-B (n=459), respectively.  RESULTS: For both two protocols, we found similar distribution of age, sex, weight, and BMI when comparing descriptive statistics (e.g., mean, standard deviation (SD)). However, LDL-C in CTs was higher than in SFs; e.g., in Protocol-A, patients without prescription for dyslipidaemia showed LDL-C (mg/dL) of 169.9±19.2 from the CT vs. 160.2±16.5 from the SF. Among the patients with prescription, LDL-C was 132.3±31.0 from the CT vs. 118.4±31.0 from the SF. A similar difference was observed for Protocol-B. This finding showed non-weighted sampling from the SF would cause biases in CTS. At the same time, this result suggested that various CTS’s assumptions by weighted sampling might be useful. Further evaluation is recommended.  CONCLUSIONS: The present study provides relevant information that there is considerable similarity in the demographics between SFs from Japanese HDB and Japanese CTs, suggesting usefulness of HDB with application of weighted sampling with CTS.