Pressure‐volume relationships for the bcc transition metals in the groups VB (V, Nb, and Ta) and VIB (Cr, Mo, and W) were determined under hydrostatic pressure to 100 kbar at room temperature by means of x‐ray diffraction, employing diamond‐anvil pressure cell and the ruby (R1line) fluorescence calibration technique. Using the measured ultrasonicK′0values, whereK0is the bulk modulus at ambient pressure, for five metals and the deduced shock‐waveK′0value for Cr, the values ofK0for V, Nb, Ta, Mo, W, and Cr are calculated to be 1.54, 1.71, 1.94, 2.67, 3.07, and 1.93 Mbar, respectively, by least‐squares fit of the experimentalP‐Vdata to the Birch‐Murnaghan equation. TheK0values thus determined are in good agreement with the ultrasonic and shock‐wave values for V, Nb, Ta, Mo, and W. For Cr, theK0value (1.93 Mbar) is in agreement with the shock‐wave value (1.92 Mbar) but not with the ultrasonic value (1.65 Mbar). This discrepancy can be explained in view of the paramagnetic→antiferromagnetic transition in Cr in the temperature proximity of the ultrasonic measurements (Neel temperatureTN∼311 °K at 1 bar) and by the negative pressure dependence ofTN.