We estimate the survival probability of J/psi in relativistic heavy-io
n collisions, using both short-distance QCD and nuclear absorption mec
hanism. The suppression is found to be almost 100 percent for a therma
lly equilibrating quark-gluon plasma. The measurement of such a huge s
uppression of J/psi may suggest the existence of a deconfined partonic
medium, possibly a thermalised quark-gluon plasma, at RHIC.