Secular gains in IQ test scores have been reported for many Western countries. This is the first study of secular IQ gains in South Korea, using various datasets. The first question is what the size of the Flynn effect in South Korea is. The gains per decade are 7.7 points for persons born between 1970 and 1990. These gains on broad intelligence batteries are much larger than the gains in Western countries of about 3 IQ points per decade. The second question is whether the Korean IQ gains are comparable to the Japanese IQ gains with a lag of a few decades. The gains in Japan of 7.7 IQ points per decade for those born approximately 1940-1965 are identical to the gains per decade for Koreans born 1970-1990. The third question is whether the Korean gains in height and education lag a few decades behind the Japanese gains. The Koreans reach the educational levels the Japanese reached 25-30 years before, and the gains in height for Koreans born 1970-1990 are very similar to gains in height for Japanese born 1940-1960. so three decades earlier. These findings combined strongly support the hypothesis of similar developmental patterns in the two countries. (C) 2011 Elsevier Ltd. All rights reserved.