[en] We reconsider the prediction of the semileptonic branching ratio of B mesons, using a recent calculation of the radiative corrections with account for finite quark masses in nonleptonic decays and taking into account 1/m_b² corrections. For the semileptonic branching ratio we obtain B_SL=(11.8±1.6)% using pole quark masses and B_SL=(11.0±1.9)% using running anti M anti S quark masses. The uncertainty is dominated by unknown higher oder perturbative corrections. We conclude that the present accuracy of the theoretical analysis does not allow to state a significant disagreement with the experimental results. However, our re-analysis of the decay b→ccs yields an increase of (35±11)% due to next-to-leading order corrections including mass dependent terms, which further emphasizes the problem of the average charm quark content of the final state in B decays. (orig.)