In the Portuguese context, the life cycle assessment of building materials is still in its infancy. So far, there is only a small number of Environmental Product Declarations (EPDs) available, all target for industrially based materials. Although vernacular earthen materials are seen as ecological materials, with low potential environmental impacts, there are no studies that allow to quantitatively compare these materials with conventional ones, according to the applicable standards. In the case of Portugal, there are no EPDs or studies for these materials and the studies available worldwide are hard to compare, since they not follow the same life-cycle assessment methodology. This paper aims at contributing to a better understanding about the environmental performance of earthen materials by presenting results from the life cycle assessment of Compressed Earth Blocks (CEBs) and Rammed earth, based on specific life cycle inventory values obtained from a producer company, following the guidance provided by the standard EN15804. Among other conclusions, results show that CEB and Rammed earth have a total Embodied Energy of 3.94 MJ/block and 596 MJ/1m3 and a Global Warming Potential of 0.39 kg CO2 eq/block and 47.5 kg CO2 eq./1m3, respectively. In a cradle-to-gate analysis of different walls, the use of earthen building elements can result in reducing the potential environmental impacts in about 50%, when compared to the use of conventional ones. Additionally, the advantages of using earthen materials are also discussed for the different building life-cycle stages, focusing on the possibility to recycle these materials in a closed-loop approach.