Future space applications include very large elements, whose in orbit configuration cannot be launched in a single flight by the existing launchers. Deployable structures present great advantages in this field, as the mass and volume savings that can be achieved are significant.SENER has carried out, under ESA contract, a study to develop, manufacture and test a deployable Large Truss Structure (LTS), that meets the requirements for the mid-term applications foreseen within the European scenario. This paper presents the design, analysis, manufacturing and test phases of a full scale three-module Engineering Model of the LTS.