Base isolation is a technology that is widely accepted by the profession as an effective means to protect structures and non-structural components against earthquake damage. This is demonstrated by the large number of buildings and bridges that have been built or retrofitted using this technology. It is contended, however, that, at present, the existing isolation systems have limitations and that these limitations have prevented a widespread use of the technology in ordinary structures and in developing and emerging countries. It is the purpose of this paper to make a brief review of the predominant isolation systems, pinpoint their major disadvantages, and describe some of the solutions that have been proposed to overcome these disadvantages. The systems considered are (a) laminated elastomeric bearings, (b) friction pendulum bearings, and (c) sliding bearings. Special attention is given to the description of two recently proposed sliding systems that incorporate unusual features: (a) hydrostatic bearings, and (b) hydromagnetic bearings. The review reveals that many researchers are still active in the base isolation field and that many interesting improvements have been proposed over the last few years.