Background: Sarcolemmal acid-base transporters maintain intracellular pH (pHi ) at neutral values. Despite its important role in various cardiovascular diseases, virtually nothing is known about acid-base transport in human myocardium. We try to identify the acid-base transporters in human cardiac myocytes. Methods: Human cardiac myocytes were isolated from atrial appendages and loaded with the pH-sensitive fluorescent dye SNARF. Results: Myocytes were subjected to acid and alkaline loads from which they were allowed to recover. Varying the ionic composition of the salines during acid load recovery revealed three different acid extruders. I) a Na⁺/H⁺ exchanger (NHE), II) a Na⁺-HCO₃^-cotransporter (NBC) and III) a Cl^-/HCO₃exchanger (AE). NHE and NBC could be inhibited by respectively 10 mM cariporide and 250 mM DIDS. In addition, varying the ionic composition of the salines during alkaline load recovery revealed three different acid loaders. I) a Cl^-/OH^-exchanger (CHE), II) a Cl^-/HCO₃^-exchanger (AE) and III) a Na⁺ driven Cl^-/HCO₃^-exchanger (NDAE). Conclusion: Like in other mammalian hearts the human heart exhibits two Na⁺ dependent acid extruders (NHE and NBC) and two Cl^-dependent acid loaders (CHE and AE). In addition, the human myocardium possesses a potent Cl^-dependent acid extruder (AE) and a Na⁺ driven acid loader (NDAE).