The different techniques used to access sin(2) theta(eff)(lep) in the
hadronic sector is presented with a summary of the results obtained by
the LEP experiments. The LEPI average in this sector is sin(2) theta(
eff)(lep)=0.23225 +/- 0.00035. The main sources of uncertainties in th
e experimental measurements are reviewed with a special attention to t
he forward backward b asymmetry.