A folding knife includes an elongated blade, an elongated handle, a disc-shaped cam, and a cam mechanism. The blade defines a cam-receiving aperture having a generally circular profile and a blade notch which is disposed adjacent to and which opens into the cam-receiving aperture. The handle includes a locking formation for releasable engagement with the blade notch. The configuration of the cam and the relative positions of the blade notch and the locking formation are such that when the blade is in the extended position, the locking formation is releasably captured in the blade notch.