Investigation of the effect of electron radiation and triallyl isocyanurate (TAIC) on the functional properties of poly(ε-caprolactone) (PCL) films was the aim of the present paper. The mechanical properties from static tensile tests, resistance to strain at elevated temperatures, permeability of oxygen and water vapor, shrinkage, luminous transmittance, haze and surface free energy were determined. It was found that irradiation of PCL containing TAIC induces larger and more distinct changes in the film properties with regard to the irradiation of PCL with no TAIC. This fact results from formation of a crosslinked structure, in which TAIC participates in linking of PCL macromolecules. The extent of observed changes essentially depends on the magnitude of the electron radiation dose. It was also found that films obtained exhibit a two-phase structure (crosslinked and non-crosslinked) in the case of samples with TAIC, and structural changes associated with elongation of macromolecules, formation of branched structures or polymer degradation in the case of samples with no this compound.