In an exhaust gas turbocharger for an internal combustion engine having a turbine wheel connected, by means of a shaft, to the compressor wheel of a compressor which includes a variable inlet geometry comprising a plunger and a sleeve-shaped partition for controlling an auxiliary duct leading radially to the compressor wheel, which is provided with compressor wheel blades to which air is supplied axially via an axial inlet passage and radially via a radial wheel inlet area, the compressor wheel includes a contoured ring provided at its outer circumferential surface with auxiliary blades disposed over, and aligned with, the compressor wheel blades in the radial and the axial wheel inlet region of the compressor wheel.