This work was adopted to study the effect of sericin-containing bath on the different structures of knitted polyester fabrics to improve some of their comfort attributes. Without appreciable deterioration in its inherent properties, the different structures of treated polyester fabric exhibited induced hydrophilicity, enhanced electrical conductivity, improved resistance to ultraviolet radiation and better water vapour permeability. Five knitted polyester fabrics of different structures were saponified by sodium hydroxide to create carboxylate ions along their macromolecules, and then treated by sericin within freshly discharged bath from degumming of raw natural silk. Treatment of polyester fabrics with sericin was carried out in presence and absence of glutardialdehyde as a crosslinking agent between polyester and sericin macromolecules. Different thermo-physiological parameters of comfort; namely thermal conductivity/resistivity, air/water permeability, release of electrostatic charges, ultraviolet protection factor, and water vapour transmission of the sericin-treated as well as untreated knitted fabrics were assessed. The mechanism of interaction between knitted polyester fabric and sericin in presence of glutardialdehyde was proposed. Scanning electron microscopy was used to ascribe any alteration in the fibre morphology. The change in the fabric crystallinity was investigated using X-ray diffraction pattern. The burst strength, bending stiffness and yellowing index of the treated fabrics were in the acceptable range.