For the past 5 decades, a bicarbonate-based approach has been the dominant method used for the diagnosis and treatment of acid-base disorders. This approach, however, has been criticized by some as (1) qualitative and not quantitative in nature and (2) incapable of detecting important diagnoses. Stewart, using principals of electroneutrality and conservation of mass, developed a "new" approach to the diagnosis and management of these disorders. The proponents of Stewart's approach believe that it not only offers a mechanistic explanation for the disorders but also provides the tool to make a more accurate diagnosis. Although Stewart's approach has been largely ignored by nephrologists and renal physiologists, it is increasingly used by anesthesiologists and intensivists. This review discusses the clinical utility of Stewart's method compared with the traditional bicarbonate-based approach. Although Stewart's method proposes a different, however not new, approach, it does not improve our ability to diagnose more accurately or manage these disorders. Stewart's method also does not provide the tool to prognosticate any better than the traditional method.