Heysen is an electoral district of the House of Assembly in the Australian state of South Australia. It is named after Sir Hans Heysen, a prominent South Australian landscape artist. It is a 1,102 km² electoral district that takes in some of the outer southern suburbs of Adelaide before fanning south-east to include most of the Adelaide Hills, as well as farming areas some distance from the capital. It includes the areas of Aldgate, Bridgewater, Echunga, Hahndorf, Macclesfield, Meadows, Stirling and Strathalbyn, as well as part of Mount Barker. Although geographically it is a hybrid urban-rural seat, it is counted as a metropolitan seat.
As Heysen combines both wealthier suburbs in the foothills of the Adelaide Hills and rural areas further east, it has been a stronghold for the Liberal Party and its predecessor, the Liberal and Country League, ever since its creation in the electoral redistribution of 1969 as a replacement for Stirling. It was first contested at the 1970 election. It was abolished at the 1977 election, forcing then-member David Wotton to move to the seat of Murray. However, Wotton returned to Heysen when it was re-established at the 1985 election. He subsequently held the seat until his retirement in 2002, when he was replaced by current member Isobel Redmond.
The 1997 election saw the Democrats receive 48.1 percent of the two-candidate preferred vote, the closest they had ever come to a seat any Australian lower house (apart from the South Australian seat of Mitcham). The 2002 election saw the Democrats receive 46 percent of the two-candidate preferred vote. The 2006 election saw their vote collapse with Labor being brought back into the two-candidate race. Out of 47 lower house seats, the SA Greens have consistently polled strongest in Heysen. Greens candidate Lynton Vonow came within a few percent of winning the overlapping federal seat of Mayo at the 2008 by-election. Vonow contested Heysen for the Greens at the 2014 election and overtook the Labor candidate coming second after preferences with a 39 percent two-candidate preferred vote from a 19.7 percent primary vote. The Greens also polled well in neighbouring seats such as Kavel and Davenport with primary votes over 15 percent.