The thermoelectric power and electrical resistance of pure bismuth nanowires have been measured in longitudinal magnetic fields up to B = 20 T at temperatures between 4.2 and 26 K. At B = 0, the 200 nm samples exhibit large values of thermopower (about +110 μ V K^-1 at 25 K), which are dominated by diffusion with no phonon drag being evident. Both the magnetoresistance and magnetothermopower show well-pronounced features generated by the diffuse surface scattering of hole carriers. In particular, the magnetothermopower offers the possibility of identifying the characteristic magnetic field, where the diameter of the hole Larmor orbit equals the wire diameter, as an extremum, in distinction from the magnetoresistance data, where the corresponding feature manifests as an inflection point. The frequencies of Shubnikov-de Haas oscillations were found to be consistent with the Fermi-surface parameters of bulk Bi. The contribution of holes to the charge transport in pure Bi nanowires is more significant than generally thought.