This study aimed to investigate national prescription trends of benzodiazepines (BZD) for adults between 2007 and 2011 using Health Insurance Review and Assessment Service (HIRA) database in South Korea. Data analysis was performed by claim unit or patient unit. For the analysis of patient unit, each claim was merged by the same patient. Defined daily dose (DDD) was used to analyze the data in terms of dose and periods of BZD prescription. We identified a total of 22,361,449 adult patients who had BZD prescription at least once in 1,989,263 claims during 5 years. The average national BZD prescription prevalence for 1 year was 23.7%, 7.9%, 4.7%, and 3.2% of >= 1 day supply, >= 30 days supply, >= 90 days supply, and >= 180 days supply, respectively. The trends for 5 years were very similar. Among study population, 87.7% visited only non-psychiatric departments and the most frequent indication was gastrointestinal related diseases. BZD consumption expressed as DDDs per 1,000 inhabitants per day was 109.2. BZD consumption tended to be ~ 4 x higher in elderly than that of non-elderly (268.6 vs. 60.0 in male and 367.7 vs. 90.9 in female). Our study indicated the possibilities for inappropriate prescription of BZD, and the limitation policy on continuous prescription over 30 days supply did not seem to be effective. The effective interventions including an educational program for appropriate prescription of BZD should be considered.