Abstract: A new thick-thin triangular plate element is presented. The element emanating from the Hellinger-Reissner variational principle has independent interpolation for slope, displacement, shear strain and bending strain. It is shown that it does not suffer from any defect common to other Mindlin plate elements. Several examples are presented to illustrate the behaviour of this new element. It is pointed out that this element is also considered as the element using the reduced integration for shear energy (i.e. 1...