Abstract: A holder or holster for a foldable knife in which the knife has a handle and a blade pivotably mounted to the handle is provided. The holster has a cam-fulcrum therein which bridges a forward portion thereof proximate the exit for the handle of the knife. The holster has a chamber therein to receive and hold the knife in a partially-folded position around the cam-fulcrum so that on withdrawal of the knife, the blade contacts and pivots around the cam-fulcrum and opens relative to the handle so that the knife is withdrawn from the holster in an open position.The holster can also have a second cam-fulcrum which bridges a rearward portion thereof so that on insertion of the knife into the holster, the back edge of the blade contacts such cam-fulcrum and is folded toward the handle as the handle advances into the holster.Accordingly, the foldable knife is automatically opened upon withdrawal from the holster and automatically folded upon insertion therein.