It is recognized that unsymmetrical optical systems can provide better or unique solutions to certain optical design problems. However, the design of unsymmetrical optical systems is considered a difficult or obscure task. There are a large number of papers published dealing with isolated aspects of unsymmetrical optics; however, the number of papers presenting a theory and method for the systematic design of a particular class of unsymmetrical optics is small. There is today a significant understanding of the imaging properties of unsymmetrical optics, but there is not a general theory to design such systems as for example in the case of axially symmetrical optics. This is due to the great diversity of configurations in unsymmetrical optics. To design unsymmetrical optics, a number of design methods are available. In this paper four design methods that are based on theories still under development are briefly discussed. Ideally, a theory must provide insight about the main image characteristics or first-order properties, about image defects or aberrations, and provide a systematic method to conduct a design. An unsymmetrical optical system is defined as a combination of optical elements such as mirrors, lenses, and gratings, that lacks an axis of rotational symmetry.