The effects of γ irradiation on the mol. wts, viscosities and methoxyl contents of apple pectins were investigated at doses of 0–10 kGy. The apple pectins investigated were samples isolated in the laboratory before and after irradiation and an industrially purified apple pectin. No changes in mol. wts of the pectins were observed when whole apples were irradiated but decreases in viscosity and methoxyl content were observed at doses of 1 kGy. When isolated pectins were irradiated, reductions also in mol. wt were detected, at the same doses.