The bioavailability of chloramphenicol and the pharmacokinetics of chloramphenicol and chloramphenicol succinate were studied in 5 premature infants (group A), 8 full-term infants (group B) and 4 children (group C) receiving intravenous chloramphenicol succinate at steady-state. Although the total body clearances of chloramphenicol succinate were similar in the three groups, its renal clearance, 0.78 ± 1.13 ml/min/kg, in group A was markedly lower than 4.11 ±2.41 ml/min/kg in group B (p < 0.05) and 7.31 ± 2.85 ml/min/kg in group C (p < 0.05). The bioavailability of chloramphenicol, 0.93 ± 0.10, in group A was considerably higher as compared to 0.71 ± 0.14 in group B (p = 0.06) and 0.64 ± 0.13 in group C (p < 0.05). The elimination half-life of chloramphenicol, 10.08 ± 6.88 h, in group A was longer than 3.48 ± 1.52 h in group B (p < 0.05) and 4.86 ± 2.41 h in group C (p = 0.06). The increased bioavailability of chloramphenicol in premature infants was a result of the decreased renal clearance of chloramphenicol succinate causing a greater fraction of the chloramphenicol succinate dose to be hydrolyzed to chloramphenicol.