Uncertainties in the determination of |V$_{cb}$|

I discuss the theoretical uncertainties in the extraction of |\, V_{cb}| from semilep\-to\-nic decays of B mesons, taking into account the most recent theoretical developments. The main sources of uncertainty are identified both for the exclusive decay mode B\to D^*\ell\,\bar\nu and for the inclusive channel B\to X\,\ell\,\bar\nu. From an analysis of the available experimental data, I obtain |\,V_{cb}|_{\rm excl} = 0.041\pm 0.003_{\rm exp}\pm 0.002_{\rm th} from the exclusive mode, and |\,V_{cb}|_{\rm incl} = 0.040\pm 0.001_{\rm exp}\pm 0.005_{\rm th} from the inclusive mode. I also give a prediction for the slope of the form factor {\cal{F}}(w) at zero recoil, which is \widehat\varrho^2=0.8\pm 0.3.