We estimate the consumer price index (CPI) bias in Korea by employing the approach of Engel's Law as suggested by Hamilton (2001). Using Korean panel data (Korean Labor and Income Panel Study) and following Hamilton's model with a non-linear specification correction, our estimation result shows that the CPI bias over the sample period (2000–05) averaged at least 0.7 percent annually, which implies that about 21 percent of the inflation rate during the sample period can be attributed to the bias. This CPI bias has caused a substantial understatement of the growth in real GDP and contributes to excessive transfers from younger taxpayers to the elderly through indexed pension payments. We discuss the implications of the CPI bias for economic management and policies in Korea.