Nyssa /ˈnɪsə/ is a city in Malheur County, Oregon, United States. The population was 3,267 at the 2010 census. The city is located along the Snake River on the Idaho border, in the region of far eastern Oregon known as the "Treasure Valley". It is part of the Ontario, OR–ID Micropolitan Statistical Area.
The primary industry in the region is agriculture, including the cultivation of Russet potatoes, sugar beets, onions, corn, flower seed, mint, and wheat. The city's economy relies on the surrounding agricultural area with its several large onion and potato packaging plants.