Abstract: An optical fiber cleaving tool comprising a base supporting a sled which is biased to carry an optical fiber clamp thereon away from an inner surface of an orthogonal end wall having extending through it in alignment with the clamp an aperture disposed to receive a fiber optic connector end portion. The connector has a terminal end surface provided with a central aperture through which an optical fiber end portion extends to the clamp on the sled for axial tensioning. Aligned with the aperture in the wall is a recess having an end surface chordally disposed with respect to the aperture for abutting engagement with the terminal end surface of the connector and serving as a reference plane. A cutter rotatably mounted above the recess end surface has a peripheral portion from which protrudes resiliently a diamond-tipped end portion of a wafer-like blade which is slidably disposed in a slot extending diametrically of the disc and having a thickness greater than the thickness of the blade.