Rotating stall alleviation in an axial compressor with deployment of air injection at its rotor blade row tip region has been experimentally investigated. Twelve air injectors had been mounted evenly spaced around the compressor casing upstream the rotor blade row. Initially, improvement of the compressor overall performance has been examined through air injection, especially at stall point condition. Instantaneous flow velocities at various radial and circumferential positions were measured simultaneously utilizing hot wire anemometry. These unsteady results, obtained from these latter measurements together with signal frequency analyses, provided to describe the stall inception process and consequent flow induced fluctuations and also alleviation process of stall during the air injection. Results show that a small amount of air injection at the rotor blade tip region can affect the total pressure rise and specifically can increase the compressor stall margin efficiently. Air injection of less than 1% of the compressor main flow rate through the injectors has caused the stall margin to be improved by 9%. Air injection at the blade row tip has caused its beneficial effects to extend throughout the blade whole span, especially while working at the near stall conditions.