  The scattering lengths of a two pion system are the {\it golden magnitudes}
to test the QCD predictions in the low energy sector. The DIRAC (PS-212)
experiment at CERN will obtain a particular combination of the S-wave isospin 0
and 2 scattering lengths by measuring the lifetime of pionium, the
hydrogen-like $\pi^+ \pi^-$ atom. This measurement tests the accurate
predictions of the Chiral Perturbation Theory. The most recent experimental
results are presented.
