At present there is no recognized standard test method that can be used for the measurement of the tensile properties of additively manufactured lattice structures. The aim of this work was to develop and validate a methodology that would enable this material property to be measured for these geometrically and microstructurally complex material structures. A novel test piece has been designed and trialed to enable lattice struts and substructures to be manufactured and tested in standard bench top universal testing machines and in small scale in-situ SEM loading jigs (not reported in this paper). In conjunction with the mechanical tests, a finite element (FEA) modelling approach has been used to help cross validate the methodology and results, and to enable larger lattice structures to be modelled with confidence. The specimen design and testing approach developed, is described and the results reviewed for AlSi10Mg.