A radial arm saw is a cutting machine consisting of a circular saw mounted on a sliding horizontal arm. Invented by Raymond De Walt in 1922, the radial arm saw was the primary tool used for cutting long pieces of stock to length until the introduction of the power miter saw in the 1970s.

In addition to making length cuts, a radial arm saw may be configured with a dado blade to create cuts for dado, rabbet or half lap joints. In addition some radial arm saws allow the blade to be turned parallel to the back fence, allowing a rip cut to be performed.

Unlike most types of woodworking machinery, the radial arm saw has a clear genesis: it was invented by Raymond De Walt of Bridgeton, New Jersey. De Walt applied for patents in 1923, which were issued in 1925. De Walt and others subsequently patented many variations on the original, but De Walt's original design (sold under the moniker Wonder Worker) remained the most successful: a circular saw blade directly driven by an electric motor held in a yoke sliding along a horizontal arm that is some distance above a horizontal table surface. A saw which combines the sliding and compound features is known as a sliding compound miter saw or SCMS.