We screened the laboratory data of 50 chronic hemodialysis patients selected randomly over a 21-month period to generate 158 data points which identified two groups: (1) those with a predialysis total CO<sub>2</sub> concentration less than or equal to 19 mEq/l (data A; n = 57) and (2) those with a predialysis total CO<sub>2</sub> concentration greater than 19 mEq/l (data B; n = 101). Then, both groups were compared for the following parameters: predialysis blood urea nitrogen (BUN), serum phosphorus, uric acid, creatinine, and albumin concentrations, Kt/V, urea reduction ratio, normalized protein catabolic rate, dry weight, ultrafiltration, blood flow and dialysis flow rates, duration of dialysis treatment, and blood pressure. Group data A had significantly higher predialysis BUN, phosphorus, and uric acid concentrations than group data B. There were significant inverse correlations between predialysis serum bicarbonate and predialysis BUN, phosphorus, and uric acid concentrations. Although it is not clear what the long term side effects of moderate metabolic acidosis are, we recommend its correction.