Determination of the acid-base status as an index of a patient' s metabolic/respiratory state is one of the most frequently conducted diagnostics in emergency medicine, intensive care medicine, and anesthesia. German training for medical specialization regardless of the discipline requires periods spent at emergency ambulances and intensive care units. Thus, proper education in acid-base (patho-) physiology is important for all medical students. Currently, two approaches to acid-base physiology and diagnostics of the metabolic state are prevailing in German textbooks: the buffer base-centered concept (BE; Siggaard-Andersen, 1974) and the HCO₃^--centered concept (Schwarz & Relman, 1963). However, these approaches often leave both teacher and learner with the impression of fragmentary comprehension and logic. Furthermore, in many clinical cases both approaches are extended by the 'anion gap' calculation, which itself requires modifications depending on circumstances (Salem & Mujais, 1992). The concept that provides a comprehensive approach and high accessibility, given the realization that we deal with a complex biological system, is the electrochemical acid-base approach, relying on fundamentals of mass balance and electroneutrality (Stewart, 1981). Emanating from the central question 'What determines [H⁺] in body fluids?' this concept integrates CO₂, electrolytes and weak acids/bases, including [albumin] (Figge et al., 1991), and results in simple but highly useful diagnostic procedures. On theoretical grounds, the electrochemical and the buffer base approach are equivalents (Wooten, 1999 & 2003), thus there is no question of scientific priority, but of didactic advantages and clinical usefulness.