The extended Omont-Ueda-Kaulakys treatment of collisional effects on quasi-Rydberg states, which takes into account the perturbation of the lower state, is applied to Ar*-He, Ar*-Ne and Ar*-Ar systems. The pressure broadening and shift coefficients of spectral lines of argon involving the 3p^{5}ns (n = 6-9) and 3p^{5}nd (n = 4-8) states are determined and compared with those resulting from the experiment.