  The parton distribution function of the pion in the valence region is
extracted in a next-to-leading order analysis from Fermilab E-615 pionic
Drell-Yan data. The effects of the parameterization of the pion's valence
distributions are examined. Modern nucleon parton distributions and nuclear
corrections were used and possible effects from higher twist contributions were
considered in the analysis. In the next-to-leading order analysis, the high-$x$
dependence of the pion structure function differs from that of the leading
order analysis, but not enough to agree with the expectations of pQCD and
Dyson-Schwinger calculations.
