From a study of the kinematic properties of the final state produced in the semileptonic decays b→Xℓνℓ , the inclusive charmless semileptonic branching ratio of b hadrons is measured. With a sample of 3.6 million hadronic Z decays recorded between 1992 and 1995 with the ALEPH detector at LEP, the value Br(b→Xuℓνℓ) is determined to be (1.73±0.55stat±0.55syst)×10−3 , where Xu represents any charmless hadronic state and b is a mixture of b hadrons weighted by their production rates. This measurement yields the result |Vub|2=(18.68±5.94stat±5.94syst±1.45HQE)×10−6, where the last error comes from the conversion of the branching ratio to the CKM matrix element squared.