Softening is a gardual decrease of mechanical resistance resulting from a continuous incresase of deformation imposed on a material speciman or structure. It is a salient feature of quasi-brittle materials like clay brick, mortar, ceramics, stone or concrete which fail due to a process of progressive internal crack growth. Such mechanical behaviour is commonly attributed to the heterogeneity of the material., due to the presence of different pkases and material defects, such as flaws and voids. For tensile failure this phenomenon has been well identified for concrete but very few results exists for clay brick. In the present paper, the results of an extensive set of tests carried out at University of Minho and including three different types of brick under uniaxila tension will be presented. Both tensile strength and fracture energy are quantified, with recommendations for the adoption of practical values.