We characterized the cerebrospinal fluid (CSF) penetration and pharmacokinetics of SCH-39304 in adult rhesus monkeys receiving a single oral dose of SCH-39304 (2.0 mg/kg of body weight). The mean CSF-to-plasma area under the curve ratio was 0.63 (±0.18, standard error of the mean); maximum concentrations were 1.34 pg/mi (±0.18) in CSF and 1.96 pg/ml (±0.43) in plasma. The mean plasma half-life was 45.7 h (±11), and mean CSF half-life was 38.7 h (±3.5). The mean levels of SCH-39304 at 24 h were 1.48 pg/ml (±0.3) in plasma and 0.96 ,g/ml (±0.12) in CSF. We conclude that SCH-39304 effectively penetrates into CSF and achieves concentrations considered active against many opportunistic yeasts and that these concentrations are sustained in CSF for .24 h.