SEA-MO is the Regional Mathematics olympiad in Southeast Asia. This competition is held by the Southeast Asian Ministers of Education Organization (SEAMEO). Currently, nine countries are participating. They are Brunei, Cambodia, Indonesia, Lao PDR, Malaysia, Philippines, Singapore, Thailand, and Vietnam. Each country is represented by four participants, one team leader, and one deputy leader.

The paper consists of 20 Individual Short Answer questions, five Individual Long Answer questions, and 10 Team questions.

The first SEA-MO was held on 14 - 18 September 1998 in Penang, Malaysia. Second SEA-MO was held on 18 - 22 June 2001 in Penang, Malaysia, at the same place. Third SEA-MO is planned to be held in 2003.