The paper contains a re-evaluation of the experimental results for the pressure dependence of viscosity obtained by Pilarczyk and described by Kestin and Pilarczyk. The re-evaluation is based on an improved theory of the oscillating-disk viscometer described by Kestin and Wang. The results for air, nitrogen, argon, helium, and hydrogen are given in graphical and tabular form as well as in the form of empirical equations. The range covered is 1 to 70 atm at 25 C. The results constitute a relative measurement which is based on Gibson and Michels’ data for nitrogen. Very good agreement with previously published data for nitrogen, air, and hydrogen has been reported. In the case of helium no comparative data could be found and in the case of argon there is good agreement with the data published by Michels and others but the difference in absolute values is somewhat higher than for the preceding three gases. The agreement as to rate of change with pressure is excellent. It is believed that the data now reported contain an uncertainty of no more than 0.2 per cent for nitrogen, air, hydrogen, and helium and of not more than 0.6 per cent for argon with respect to nitrogen. The data have been summarized in Table 1.