We have studied the thermoelectric power and the resistance of (TMTSF)2PF6 as a function of temperature and magnetic field in the region of the spin-density-wave (SDW) metal-insulator transition. We observe slight changes above TSDW. Below TSDW the anomalous thermopower observed in the absence of a magnetic field is suppressed and the material behaves more as a conventional semiconductor. The effect of the magnetic field is in the orbital motion of the carriers as the significant changes are observed only when the magnetic field is aligned along the c axis. These results are compared with previous magnetotransport measurements in this family of organic conductors. © 1985 The American Physical Society.