Hillcrest is a suburb of Adelaide in the City of Port Adelaide Enfield local government area. It is around 10 km northeast of the city centre. It was best known as the location of the Hillcrest Hospital, a state government institution for people suffering mental illness that took up most of the suburb's area before the northern part of the suburb was renamed Gilles Plains, but the remainder of this institution and its converted former buildings are now within the suburb of Oakden.