Nifurtimox disposition was evaluated in 7 healthy volunteers. Each subject received an oral dose of 15 mg/kg of nifurtimox and blood sample was obtained 11 h after the drug administration. We used an analytical method previously assessed in the literature. The pharmacokinetic analysis was carried out according to a one-compartment model and the most important parameters established were elimination half-life, distribution volume, and clearance. Serum concentrations were low in relation to the high doses administered. The low serum concentration is probably the result of a marked first pass effect.