Hypocalcemia has been documented in critically ill patients, including those with sepsis and shock. However, its incidence and significance in bacteremic patients without shock has not been established. In the present study the presence of hypocalcemia was evaluated in a group of 67 consecutive bacteremic patients, as compared with 64 infected but nonbacteremic patients. After correction of serum calcium level for serum protein, 25 of the bacteremic patients (37.3%) had "corrected" hypocalcemia (less than 8.5 mg/dL [2.12 mmol/L]), compared with only three in the nonbacteremic group (4.5%). The incidence and magnitude of hypocalcemia in gram-positive and gram-negative infections was similar. In hypocalcemic patients, the "corrected" calcium level was found to be inversely correlated with day of disease and attained a nadir on day 6 to 8 of bacteremia. This nadir was significantly lower in male than in female subjects. Hypocalcemic patients had a significantly higher maximal temperature than normocalcemic ones, but hypocalcemia was unrelated to serum levels of albumin, transaminase, and creatinine.