An experimental investigation of aerodynamic drag reduction by counter flow plasma jet injection from the stagnation region of a hemispherical blunt cylinder model flying at hypersonic Mach numbers are presented. Experiments are carried out in a hypersonic shock tunnel at four different jet- to-pitot pressure ratio and different supply powers. The flow fields around the test model are visualized using high speed schlieren technique. Direct force measurement is also performed using a single component accelerometer balance. The weakly ionized argon plasma jet has an electron temperature around 6400K and electron number density ∼4.9×1015 cm-3. With plasma jet at pressure ratio 72.5 and 1.8 KW supply power the reduction in drag is found to be ∼28% (more than its cold jet counter part) although the plasma jet momentum is less than its cold jet counter part. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc.