The rapid cost escalation of the government employee scheme in Thailand was driven by the overprescription of non-essential drugs (NEDs), which were not listed in the National Lists of Essential Medicines. A restrictive reimbursement policy implemented in October 2012 required prescribers to base the prescription of NEDs on six criteria, including A and B for safety, C for effectiveness, D for availability, and E and F for costs, hence known as the A-F policy.The A-F policy was examined in terms of its outcomes regarding the prescription volume and reimbursement expenditure for lipid-lowering drugs (LLDs).Data on LLD prescription in 2012-2015 from outpatient settings in 29 public hospitals were standardized using quantities based on the World Health Organization's Anatomical, Therapeutic and Chemical (ATC) classification and the defined daily dose (DDD) system. The policy effects were estimated using an interrupted time-series analysis.The restrictive reimbursement policy decreased both the prescription volume and the reimbursement value of non-essential LLDs. Within the first month of policy implementation, the percentage of NEDs, as defined by DDDs and reimbursement expenditure, immediately decreased by 15.1 and 15.2% points in provincial hospitals and by 8.3 and 4.4% points in military hospitals, respectively. The prescription of NEDs continued to decrease thereafter, despite there being no statistically significant changes in the trend of decreased prescribing compared with the prepolicy period. The decrease in the prescription of NEDs resulted in the declining reimbursed amount per day and stable expenditure of LLDs as a whole.The effectiveness on the A-F restrictive reimbursement on NED prescribing helped stabilize the expenditure on LLDs.