An exhaust-gas turbocharger for an internal combustion engine has a turbine in the exhaust-gas tract and a compressor, driven by the turbine, in the intake tract, the turbine having a flow channel with a radial flow-inlet cross-section and a semi-axial flow-inlet cross-section, and a flow ring being provided which limits the two flow-inlet cross-sections. The turbine is furnished with variable turbine geometry for the changeable adjustment of the flow-inlet cross-section. To improve efficiency, the position of the flow ring in the housing of the exhaust-gas turbocharger is variably adjustable.