Let FEB be a
Hurewicz fibration. The homotopy lifting property defines (up to homotopy) an
action of the H-space ΩB on the fibre F which makes H∗(F) into a H∗(ΩB)-module.
Suppose B is connected. We prove that if EB is the cofibre of a map g : W → E
where W is a wedge of spheres, then the reduced homology of F, H∗(F) is a free
H∗(ΩB)-module generated by H∗(W). This result implies in particular a
characterization of aspherical groups.