The relative bioavailability of intravenously administered chloramphenicol succinate and orally administered chloramphenicol palmitate was compared in 18 children, age 2 months to 14 years. The area under the serum concentration vs time curve of chloramphenicol and urinary excretion of chloramphenicol succinate were determined in each child under steady-state conditions while receiving chloramphenicol succinate and again while receiving chloramphenicol palmitate. The mean AUC was significantly greater during oral therapy compared to intravenous therapy (110 vs 78 mg hr/L, P less than 0.001). The relative bioavailability of chloramphenicol succinate was 70% compared to chloramphenicol palmitate. This could be explained by the mean loss of 36% of the intravenous dose in the urine as unhydrolyzed chloramphenicol succinate. The intravenous dose of chloramphenicol succinate did not correlate with AUC (r = 0.193). However, there was a significant correlation between the oral dose of chloramphenicol palmitate and AUC (r = 0.429, P = 0.025). The bioavailability of orally administered chloramphenicol palmitate is superior to that of chloramphenicol succinate given intravenously. Furthermore, there is a greater correlation between dose and amount of active drug in the body when the oral preparation is used. Oral administration of chloramphenicol palmitate appears to offer significant therapeutic advantages in patients who can tolerate medication given orally.