We report an application of the general formalism of density functional theory (DFT) for quantum fluids at finite temperature to the case of helium. Using this approach, we compute the liquid-vapour coexistence curve and the surface tension of helium at low temperatures. We observe that the range of the interface is much larger than the usual 10-90 surface thickness, and we find that the DFT reproduces the T 7 / 3 temperature dependence of the surface tension. This implies that capillary-wave effects are, at least partially, accounted for by the density functional.