We give a review of the theoretical status of the lifetime predictions in the standard model. In case of $(\Delta \Gamma/ \Gamma)_{ B_s}$ we are already in a rather advanced stage. We obtain $(\Delta\Gamma/\Gamma)_{ B_s}=(9.3^{ +3.4}_{ -4.6})%$. It seems to be difficult to improve these errors substantially. In addition now some experimental results are available. For $\tau_{ B^+}/\tau_{ B_d}$ and $\tau_{ \Lambda_b} / \tau_{ B_d}$ the theoretical status is much less advanced and the discrepancy between experiment and theory still remains. We conclude with a what-to-do-list for theorists.
Categories: hep-ph hep-ex