Preliminary results on the W boson helicity fractions at
center-of-mass energies of up to 208 GeV are presented. The fractions
of the different W helicity states, -1, +1 and 0, are determined.
Combining all data the fraction of longitudinally polarised W bosons
is measured to be $0.243 \pm 0.027 (stat) \pm 0.012 (syst)$ at an average
centre-of-mass energy of 197 GeV, in agreement with Standard Model
expectations.