Hillhouse Avenue is a street in New Haven, Connecticut, famous for its many nineteenth century mansions, including the president's house at Yale University.

The avenue ran from the Green at Temple Street to a hilltop location where James Abraham Hillhouse built the family mansion, Highwood (later called Sachem's Wood), in 1828.

Because of the nature of the street, its lots, and its orientation to the nine-square-grid of New Haven (the nation's first planned city), Hillhouse Avenue is sometimes considered to be the first suburb in the United States.

In time, Hillhouse Avenue came to be divided into an upper, residential area, and a lower portion for public buildings and the Farmington Canal.

The area at the end of the avenue where Hillhouse's mansion stood is now part of the Science Hill section of Yale's campus.