The South Orange Open, formerly known as the Eastern Grass Court Championships, is a defunct Grand Prix affiliated tennis tournament played from 1970 to 1983. It was held in South Orange, New Jersey in the United States and played on outdoor grass courts from 1970-1974, and then played on outdoor clay courts from 1975 to 1983. There were men's and women's singles tournaments, as well as men's, women's, and mixed doubles.