This study analyzes the patterns of knowledge spillovers between frontier and laggard firms in Korea using patent citation data over the period 2002-2016. Frontier firms are defined as large firms as well as global firms engaged in international patenting. The analysis reveals that the frequency with which laggard firms cite the patents of frontier firms remain very low, while the frequency with which frontier firms cite the patents of laggard firms has decreased significantly during the sample period. These findings point to poor spillover effects as a source of economic concentration in Korea.