In 2004, he signed with the Chicago White Sox as a free agent, and marked a 2.31 ERA in 56 games, along with 19 saves. His first major league appearance came against Hideki Matsui, whom he had faced numerous times in the Japanese Central League. Matsui's first home run in Japan had come off Takatsu in the same game in which Takatsu recorded his first career save. Takatsu finished second in AL Rookie of the Year voting behind Bobby Crosby. Takatsu did not pitch well the next season, and was demoted to the minors, and cut in August. He signed a minor league deal with the New York Mets, and made his way up to the majors, but was dropped at the end of the season.