Abstract: A flexible coupling for connecting a pair of rotating elements, comprising a body part (10) adapted at each end to receive part of the rotating elements, and comprising four slits (20a) each slit being longitudinally and angularly spaced from the other slits, each slit terminating in a concave face (24). The invention provides advantages over known flexible couplings since the provision of arcuate and concave end faces on each slit produces an increased material overlap with adjacent slits which decreases variations in torsional stiffness but does not affect the flexibility of the coupling.