Measurements of grid turbulence have been obtained for grid Reynolds numbers ranging from 2·4 × 106 to 1·2 × 105. The decay law and the effect of Reynolds number on the turbulence level are established. The measured power spectra of the turbulence are consistent with Kolmogoroff scaling for kη > 0·1 (k is the wave-number and η is the Kolmogoroff length); but for kη < 0·1, the spectra of the stream-wise turbulence velocity component and of the cross-stream component do not appear to be isotropically related. However, the stream-wise spectrum does display a $-\frac{5}{3}$ region, which increases in extent with increasing Reynolds number.