  Data on hadron production at high transverse momentum ($p_T>$ 2 GeV/$c$) in
p+p, d+Au, and Au+Au collisions at $\sqrt{s_{NN}$ = 200 GeV from the PHENIX
experiment at RHIC are reviewed. The single inclusive spectrum of light hadrons
produced in central Au+Au reactions shows significant differences compared to
p+p and d+Au collisions, and provides interesting information on the properties
of the underlying QCD medium present in heavy-ion reactions at collider
energies.
