The GS Caltex Maekyung Open, as it is known for sponsorship reasons, is a professional golf tournament that takes place in Seoul, South Korea. It was established in 1982, replacing the Korea Open as the South Korean event on the Asia Golf Circuit. Between 1999 and 2009 (except for 2004) it was a stop on the Asian Tour, and then in 2010 it became part of the OneAsia Tour schedule. In 2018 and 2019 it once again became a fixture on the Asian Tour. In 2005, Korean won the tournament and set an Asian Tour record as the oldest winner on tour at 50 years and 145 days.