  We review the theory that predicts that the decay constant of the excited
light pseudo-scalar mesons are suppressed in the chiral limit relative to the
pion decay constant. We compute the decay constant of the first excited pion
($\pi^\prime$) using unquenched QCD at a fixed lattice spacing with sea quarks
of mass as low as a third the mass of the strange quark. The final result is
very sensitive to the improvement conditions. We obtain $f_{\pi^\prime} /
f_{\pi}$ = 0.078(93) in the chiral limit.
