In the present study, the shape of a cruciform type specimen under biaxial loading conditions is optimised. The basic goal is to achieve uniform biaxial failure in the centre of the specimen and minimise undesirable phenomena, such as premature failure outside the area of interest and non uniformities on the central strain field, caused by stress concentrations. A numerical optimisation technique (sequential quadratic programming or SQP) is coupled with a parametrically built finite element model (FEM) to concentrate and initiate damage in the centre and achieve a uniform strain field by varying the geometrical characteristics of the specimen. The outputs of the optimisation process are compared with a commonly used cruciform type geometry.