A wire saw is a saw that uses a metal wire or cable for cutting. Industrial wire saws are usually powered. There are also hand-powered survivalist wire saws suitable for cutting branches. Wire saws are classified as continuous (or endless, or loop) or oscillating (or reciprocating). Sometimes the wire itself is referred to as a "blade".

Wire saws are similar in principle to band saws or reciprocating saws, but they use abrasion to cut rather than saw teeth. Depending on the application, diamond material may or may not be used as an abrasive. The wire can have one strand or many strands braided together (cable). A single-strand saw can be roughened to be abrasive, abrasive compounds can be bonded to the cable, or diamond-impregnated beads (and spacers) can be threaded on the cable. Wire saws are often cooled and lubricated by water or oil.