Ionization currents in spectroscopically pure helium between plane parallel silver electrodes at separations up to 0.75 cm were measured in the range 6 leq E/p leq 100 v cm^-1 mmHg^-1 and 3 leq p leq 115 mmHg where E is the applied electric field and p the gas pressure. The values of the primary ionization coefficient α/p deduced from these measurements were lower than previously published experimental values, particularly at the lowest range of E/p. Within the limits of experimental error α/p was found to be a function of E/p only.The present values of α/p were in good agreement with the values calculated by Dunlop in 1949, by Abdelnabi and Massey in 1953 and by Phelps in 1960. This result suggests that the Smit distribution of electron velocities, Maier-Leibnitz's inelastic collision cross section data and Nielsen's electron mobility values are applicable to the data.