We present a new measurement of the spin-dependent structure function gd1 of the deuteron from deep inelastic scattering of 190 GeV polarized muons on polarized deuterons. The results are combined with our previous measurements of gd1. A perturbative QCD evolution in next-to-leading order is used to compute gd1(x) at a constant Q2. At Q2 = 10GeV2, we obtain a first moment Γd1 = ∫10 gd1dx = 0.041 ± 0.008, a flavour-singlet axial charge of the nucleon a0 = 0.30 ± 0.08, and an axial charge of the strange quark as = -0.09 ± 0.03. Using our earlier determination Γp1, we obtain Γp1 - Γn1 = 0.183 ± 0.035 at Q2 - 10GeV2. This result is in agreement with the Bjorken sum rule which predicts Γp1 - Γn1 = 0.186 ± 0.002 at the same Q2. © 1997 Published by Elsevier Science B.V.