This paper examines whether adoption of International Financial Reporting Standards is associated with accounting quality in Korea by classifying all listed firms into KOSPI and KOSKAQ to test the difference of accounting quality between K-IFRS and KGAAP. We provide evidence on the effects of mandatory IFRS adoption on income smoothing, benchmark earnings management, and reporting aggressiveness (proxied by timeliness of loss recognition) using a sample of more than 1,030 firms in Korea that adopted IFRS in 2011. We compare KOSPI firms` earnings with earnings for KOSDAQ firms which exhibit more evidence of smoothing, greater tendency to manage towards a target, and less timely recognition of losses after IFRS adoption in 2011. Our findings contrast with prior studies that document evidence suggesting an increase in accounting quality after IFRS adoption.