The South Luzon Expressway (SLEX), signed as E2 of the Philippine expressway network and R-3 of the Metro Manila arterial road network, is a controlled-access highway that connects Metro Manila to the provinces in the Calabarzon, Mimaropa and Bicol Region on the island of Luzon in the Philippines. The expressway has a length of 49.56 km, traveling from its northern terminus at the Magallanes Interchange in Makati to its southern terminus at Santo Tomas, Batangas, connecting it to the Southern Tagalog Arterial Road. A portion of the expressway from the Magallanes Interchange to the Calamba Exit is part of Asian Highway 26 of the Asian highway network. It will be the longest expressway in the Philippines starting with the completion of Toll Road 4, surpassing the Subic–Clark–Tarlac Expressway (SCTEX).

The Philippine expressway network, also known as the High Standard Highway Network, is a controlled-access highway network managed by the Department of Public Works and Highways (DPWH) which consists of all expressways and regional high standard highways in the Philippines.