Separation factors of tracer amounts of Am from micro lanthanides (La, Ce, Pr, Nd, and Sm) by purified Cyanex 301 extraction in nitrate media have been determined : SFAm/La similar to 3500, SFAm/Ce,Pr similar to 1000, SFAm/Nd similar to 1900, and SFAm/Sm similar to 4500, with an average value >2300. The distribution ratio decreases with increasing lanthanide concentration in the aqueous phase. In the presence of a macro amount of Pr + Nd (0.1 similar to 0.6 M) the separation factors SFAm/Eu and SFAm/Pr+Nd are about 4.7 x 10(3) and 2.1 x 10(3), respectively. The results of the countercurrent fractional process show that by using three extraction stages and two scrubbing stages, >99.99% Am can be separated from a tracer amount of Eu with <0.1% extraction of Eu. Using six extraction stages, >99.99% Am and <0.6% macro amount of Pr + Nd are extracted into the organic phase.