Abstract: A swivel knife that is convertible for use as a conventional knife wherein the blade is rigidly mounted. A tubular housing having front and rear ends has an elongated generally cylindrical stem mounted therein and normally rotatable with respect thereto. The stem has a blade-holding end at the front of the housing and a free end at the rear of the housing. The stem is proportioned at the free end to be radially spaced from the housing. A cap member is provided in the shape of a hollow generally cylindrical shell proportioned to be forcibly inserted in the space between the housing and the free end to prevent relative rotation of the stem in the housing.