As one of South Korea's youngest swimmers, Lee qualified for two swimming events at the 2004 Summer Olympics in Athens, by achieving FINA A-standard entry time of 2:31.32 (200 m breaststroke) from the Dong-A Swimming Tournament in Seoul. In the 100 m breaststroke, Lee challenged seven other swimmers on the third heat, including two-time Olympian İlkay Dikmen of Turkey. She edged out New Zealand's Annabelle Carey to take a seventh spot and thirty-third overall by 0.29 of a second in 1:12.93. In her second event, 200 m breaststroke, Lee placed twenty-fourth overall on the morning's preliminaries. Swimming in the final heat of five, she rounded out a field of seven swimmers to last place in 2:34.55, more than three seconds off her entry time.