Gamma-irradiation techniques for improving the creep performance of polyethylene tapes (draw ratio 6.5) have been investigated. With acetylene present during irradiation, the optimum dose required for maximum suppression of yielding under tensile stress coupled with minimum embrittlement was found to be 5–10 kGy. This is one-tenth that required for irradiation in vacuum. Creep performance was also improved at 100 °C. Creep experiments at higher loads have shown that the optimum acetylene-sensitized treatment is more effective in reducing creep rate than the optimum vacuum-irradiation treatment.