The magnetoresistance, Hall effect, and electrical conductivity of bismuth have been investigated to 90 kbar. In phase I, the application of pressure decreases the number of carriers; pressure increases the hole mobility so that both electrons and holes are approximately equally mobile just before the I–II transformation occurs. These observations may be explained by an upward shift of the light carrier bands relative to the heavy carrier bands. The magnetoresistance and Hall coefficients indicate simple metallic behavior for phases II, III, and IV.