Metabolic acidosis is a well-recognized complication of chronic hemodialyzed patients. The metabolic acidosis in stable hemodialyzed patients is mainly resulted from the consequences of the inability to excrete nonvolatile acid and the patients daily protein intake. So severe metabolic acidosis in patients on hemodialysis is known as an independent determinant of protein catabolic rate and high mortality rate but the moderate degree of metabolic acidosis in stable patients on maintenace hemodialysis can be explained by the patients nutritional status. On the other hand, patients having adequate daily protein intake could have lower total CO2 levels than those of patients having inadequately lower daily protein intake. To identify this relationship, we analyzed correlations between pre-hemodialysis total CO2 and various factors reflecting the patient's nutritional status in 37 patients on stable hemodialysis. The total CO2 was ranged from 15.6 to 26.5mMol/L. Among various factors, total CO2 had negative linear correlation with normalized protein catabolic rate(nPCR) reflecting the patient's daily protein intake indirectly(Y= -0.0371X+1.75, r=-0.1319, P=0.014). Moreover, metabolic acidosis having CO2 lower than 18mMol/L may modulate protein kinetics as showing steeper slope than those of more than 18mMol/L(Y=-0.1321 X +3.342, r2=0.1074 vs Y=-0.03373X+1.7543 r2=0.1001, P=0.0001). However other factors including serum albumin, body mass index, pre-hemodialysis BUN, and Kt/V, had no correlation with the total CO2. The result suggested that moderately lower pre- hemodialysis total CO2 ranging from 18 to 26.5 mMol/L was usually resulted from the high intake of the patient's daily protein intake and should be of no concern in stable patients on maintenance hemodialysis and it may use as a parameter of nutritional status. However metabolic acidosis having CO2 lower than 18mMol/L may modulate protein-kinetics, which may make the protein catabolic rate increased and can not reflect the patient's nutritional status. But it should be recommended that further studies should be needed to confirm this factor.