  Transversity distribution describes the quark transverse polarization inside
a transversely polarized nucleon. It is the less known leading-twist piece of
the QCD description of the partonic structure of the nucleon. Transversity can
be extracted from semi-inclusive deep inelastic scattering (SIDIS) where,
however, it couples to a new, unknown fragmentation function, called Collins
function. We present the preliminary results of the measurement of the
azimuthal asymmetries in the process e^+e^- -> qqbar -> pi pi X, where the two
pions are produced in opposite hemispheres. These preliminary results are based
on a data sample of about 45 fb^{-1}, collected by the BABAR experiment at a
center-of-mass energy of 10.54 GeV, and are compared with the Belle
measurements.
