Lee Hyo-jung (Korean: 이효정; Hanja: 李孝貞; Korean pronunciation: [i.ɦjo.dʑʌŋ]; born 13 January 1981) is a South Korean former badminton player.
She won the gold medal in badminton mixed doubles at the 2008 Summer Olympics with her partner, Lee Yong-dae. Lee Hyo-jung and Lee Yong-dae were unseeded, and in the finals they beat the top seeds and 2005 and 2007 world champions Lilyana Natsir and Nova Widianto of Indonesia, 21-11, 21-17.
Lee Hyo-jung also won the silver medal in badminton women's doubles at the aforementioned Olympics with Lee Kyung-won; they were seeded fourth and lost to the second-seeded Chinese pair, Du Jing and Yu Yang.
Lee became the first woman in Korean history to win gold medals at both the Olympics and the Asian Games. In the 2010 Asian Games, she partnered with Shin Baek-cheol instead of her usual partner, Lee Yong-dae. After winning the medal, she announced her retirement despite many pleas from her coaches and fans at home to continue playing until the London Olympics in 2012.