Abstract Medium-energy ion scattering (MEIS) has been used to investigate the room-temperature structure of clean Al(110). The motivation for this work was the presence of a significant discrepancy between two previous independent low-energy electron diffraction results concerning the sign of the third-to-fourth layer relaxation. We find a damped oscillatory contraction–expansion for the first three interlayer spacings. The relaxation results are (in percent change from the bulk interlayer spacing): Δ d 12=−8.5±1.0%, Δ d 23=+4.8±1.2% and Δ d 34=−3.9±1.4%. These results are compared with other theoretical and experimental values.