A motor vehicle dashboard crossbeam includes a tubular beam made in a single piece provided to extend between the A posts of the structure of the motor vehicle substantially in a transverse direction of the motor vehicle and means for fastening a or each end section of the beam on an A post. The fastening means includes a first and second fastening opening in the longitudinal direction, the first opening being formed through the beam. The fastening means also includes a fastening member attached on the end section, the second fastening opening being formed through the fastening member.