It is demonstrated that well-defined Raman spectra can be obtained from the dragline silk of the spider Nephila edulis, and that the Raman bands also shift when the silk fibre is subject to mechanical deformation. This indicates that the protein molecules in the spider silk fibre undergo direct molecular deformation when the fibre is stretched. Hence, we demonstrate that the deformation behaviour of this natural polymer fibre is similar to that of high-performance synthetic polymer fibres.