In recent years two major attempts have been made to develop ‘eco-city prototypes’ the Dongtan City in China and the Masdar City near Abu Dhabi. Both attempts have revolved round the premise that advanced post-modern technology, innovative urban planning, reliance on renewable energy, and emphasis on ‘total’ reuse can combine to achieve ‘zero carbon–zero waste’ existence. The plan of the two cities had also integrated strong business interests into the system, aiming to make ‘zero carbon–zero waste’ a kind of catch-phrase or a fashion statement that would enhance the value of the real estate the two eco-cities were planning to offer. The paper recapitulates the objectives that were set and assesses the present status of realization of those objectives. There is an already substantial and widening gap between the promise and the performance in both the cases; the review identifies the gaps and the possible reasons of their occurrence. It is highlighted that the expectation of a zero-waste existence is inherently flawed because the Second Law of Thermodynamics makes it impossible to attain. The paper brings out that no ‘eco-city’ concept can be translated into reality unless and until the inhabitants of the eco-city are prepared to voluntarily and consistently observe certain restrictions on resource consumption and to sacrifice some of the basically illusory but highly fancied ‘comforts’ which drive consumption in conventional habitations. It follows that many of those measures that are sought to be introduced in the eco-cities to make them cleaner and greener can very much be implemented in existing cities if only the same extent of voluntary participation from the lay public can be invoked that is expected in the ‘eco-cities’.