Plasma modifications were applied on the inner surfaces of high-density polyethylene bottles. The methods applied include Ar gas plasma treatment, plasma polymerization with tetrafluoroethylene (TFE), trimethylsilane (TMS) + O-2 (1:4), CH4, and C2H2 monomers, plasma-induced acrylic acid grafting polymerization, and C2H2 plasma polymerization plus acrylic acid plasma polymerization. Solvent weight-loss data are reported primarily for the n-hexane/HDPE bottle system. The best permeation reduction factor of 0.03 was obtained with C2H2 plasma polymerization at a high energy level followed by acrylic acid plasma polymerization at a low energy level. C2H2 plasma polymerization at an energy level of 10(10) J/kg and C2H2 plasma polymerization followed by acrylic acid grafting polymerization offer a similar permeation reduction factor of 0.07. A combination of improved surface polarity and tightness of the surface is responsible for remarkable reductions in permeation rates.