Turbulence intensities in a closed rectangular channel were measured under the influence of a transverse magnetic field in the range of Reynolds numbers between 5.3 × 104 and 2.8 × 105 and Hartmann numbers between 0 and 1500. The intensities were found to be suppressed exponentially by the field in the range M2/Re <0.12. Skin-friction measurements were also obtained during the experiment. The measurements were found to be lower than the theoretical magneto-fluid-mechanic laminar predictions for values of M/Re > 25 × 104. This phenomenon was attributed to magnetic entrance effects.