Houses constructed using straw bales have typically been built from wheat, rice, or barley straw, depending on local availability. Miscanthus is a perennial biomass crop with a high lignocellulose content that is grown on agriculturally marginal land. We describe the construction and as-built performance of what we believe to be the world’s first Miscanthus straw bale building. We describe the practical differences in working with the material that arise due to the slightly different physical properties of the baled material. The moisture content of the walls 17 months after construction was 11.3 ± 0.5% (pre-construction 10.72 ± 0.4% n.s.d). The in situ U value of the wall was 0.162 W/m²K, which compares to a reported U value of 0.189 W/m²K in wheat straw bale buildings of comparable wall thickness. Given the greater resistance of Miscanthus to biodegradation than wheat straw, its wider use as a construction material should be considered.