The longitudinal polarization of the Lambda(b) baryon is measured at the LE
P e(+)e(-) collider by DELPHI. It is determined from the charged lepton and
neutrino energy spectra in 249 +/- 19 Lambda(b) semileptonic decays recons
tructed in approximate to 3.5 million hadronic Z(0) decays using Lambda(0)-
lepton correlations. The measured polarization is: P-Lambda b = -0.49(-0.30
)(+0.32)(stat.) +/- 0.17(syst.). (C) Elsevier Science B.V. All rights reser
ved.