Single ﬁbre ﬂexibility is widely recognised as an important parameter in the papermaking process. A novel ﬂow cell based method for its measurement was developed at the Institute for Paper, Pulp and Fibre Technology at Graz University of Technology. A special ﬂow channel geometry is used to induce high shear forces in a laminar ﬂow regime. The movement of single ﬁbres passing the highly sheared region is recorded by means of a high speed image acquisition system. Based on the reactions of the ﬁbres to the ﬂuid forces a ﬂexibility parameter is determined for each evaluated ﬁbre.