This article reviews specific aspects of the pharmacokinetics and clinical toxicity of thiamphenicol. Studies on the systemic bioavailability in humans of 2.5 g of thiamphenicol given orally showed mean peak levels in plasma of 16.1-18.6 micrograms/ml after about 2 hr, and plasma concentrations of thiamphenicol of greater than 2 micrograms/ml for approximately 17-20 hr. The oral dose of 2.5 g appeared no less bioavailable than the usual 0.5-g parenterally administered dose. The distribution of thiamphenicol to selected urogenital tissues is also summarized. Clinical data on toxicity obtained during 1980-1982 confirmed that thiamphenicol does possess a hematopoietic suppressant potential of the dose-related type, which appeared to be observed only after repeated dosing. On the other hand, thiamphenicol does not appear to be associated with the dose-unrelated, delayed type of hemotoxicity known to occur after therapy with chloramphenicol.