  Exclusive semileptonic B decays to orbitally and radially excited charmed
mesons are investigated in the first order of the heavy quark expansion. The
emerging leading and subleading Isgur-Wise functions are calculated in the
framework of the relativistic quark model. It is found that both relativistic
and the 1/m_Q corrections play an important role and substantially modify
results. An interesting interplay between different corrections is observed.
