Optical fiber test probes test the optical functions of light-emitting circuit elements or displays, or are used in optical test fixtures. In one embodiment, an optical fiber test probe comprises an optical fiber in two sections in which both are movable with a receptacle against the bias of a compression spring during testing. One fiber is contained within a removable barrel so it can be replaced by removing it from the receptacle independently of the compression spring. In their operative test position, the two optical fibers are mounted in the receptacle to maintain light-tight optical continuity during testing. In another embodiment, an optical fiber test probe comprises a barrel and an optical fiber contained within a plunger movable in the barrel, in which a free end portion of the optical fiber extends unsupported through a compression spring which applies a spring bias to an internal end of the plunger. The fiber optic probe is isolated from loads imposed on the plunger during repetitive testing with the probe. A further embodiment comprises a fiber optic test having a low compliance, one-piece, spring loaded, molded plastic optical fiber retainer.