Determination of the upper limit on m_nu_tau from LE

A review of the direct determinations of the upper limit on the tau-neutrino mass from the LEP experiments is given. The experimental methods, the results and the comparison with non LEP measurements are also discussed. The study of the systematic errors shows that the LEP results are statistically limited so that their combination will improve the sensitivity to a massive tau-neutrino. An unofficial combination of the ALEPH and OPAL measurements gives a 95% confidence level upper limit of 15 MeV on the tau-neutrino mass.