We have performed an ab initio molecular dynamics (MD) simulation of the structure of liquid hydrogen fluoride. Our results exhibit a strong contraction of the hydrogen bond in going from the gas to the liquid phase. The local structure of the liquid resembles that of the solid with the appearance of short lived hydrogen-bonded zig-zag chains. We have also studied the dynamical properties of the system. When compared with previous MD and Monte Carlo simulations based on empirical potentials our calculations allow us to resolve old controversies.