We calculate wind mass-loss rates in main-sequence B stars. The calculations are based on our radiatively-driven NLTE wind models. The main sequence mass-loss rate depends strongly on effective temperature. For the hottest B stars the mass-loss rate amounts to 10(-9)M(circle dot) yr(-1), while for the coolest ones it is lower by three orders of magnitude. Main sequence B stars with effective temperatures lower than about 15000K (i.e., later than spectral type B5) do not have a homogeneous line-driven wind. The wind mass-loss rate also strongly depends on the chemical composition; it may either increase or decrease with increasing abundances, depending on whether the emergent flux redistribution is significant or not.