The temperature dependency of the low-density viscosity coefficients, nt, of helium and of nitrogen, 100 deg. to 1,000 deg. K, is correlated with empiricial equations, and the temperature and composition dependencies of the low-density viscosity coefficients, nt, of helium-nitrogen mixtures are correlated with the chapman- enskog expressions by using the Lennard-Jones (6:12) potential function. The residual viscosity, nt,p--nt (the difference between the viscosity of a compressed gas and the dilute gas at a given temperature), was found to be a function of the thermal pressure coefficient, (ap/at)v, and two parameters, a and b, which are characteristic of gas composition. The equation nt,p = nt + a [ap/at)v]b represented 1,340 higher pressure experimental viscosity values with a mean absolute deviation of 0.86 percent, and this equation was used to compute viscosities of the gaseous helium-nitrogen for a range of temperatures and pressures. Tabular viscosities for helium, nitrogen, and 13 helium-nitrogen mixtures are presented for 110 temperatures, 133 deg. to 740 deg. K, and 49 pressures in the range 1 to 240 atmospheres. It is estimated that uncertainties in the computed viscosity values are +/-5 percent for the region 325 deg. to 740 deg. K, +/-2 percent for the region 183 deg. to 325 deg. K, and +/-5 percent for temperatures below 183 deg. K. The latter uncertainty may rise to +/-10 percent as critical conditions are approached.