Mitochondrial ATP synthases form dimers, which assemble intolong ribbons at the rims of the inner membrane cristae. We re-constituted detergent-purified mitochondrial ATP synthase dimersfrom the green algaPolytomellasp. and the yeastYarrowialipolyticainto liposomes and examined them by electron cryo-tomography. Tomographic volumes revealed that ATP synthasedimers from both species self-assemble into rows and bend thelipid bilayer locally. The dimer rows and the induced degree ofmembrane curvature closely resemble those in the inner mem-brane cristae. Monomers of mitochondrial ATP synthase reconsti-tuted into liposomes do not bend membrane visibly and do notform rows. No specific lipids or proteins other than ATP synthasedimers are required for row formation and membrane remodelling.Long rows of ATP synthase dimers are a conserved feature ofmitochondrial inner membranes. They are required for cristaeformation and a main factor in mitochondrial morphogenesis.