  We confront the hypothesis of chemical freeze-out in ultra-relativistic
heavy-ion collisions with the hypothesis of large modifications of hadron
masses in nuclear medium. We find that the thermal-model predictions for the
ratios of particle multiplicities are sensitive to the values of in-medium
hadronic masses. In particular, the $\pi^+/p$ ratio decreases by 35% when the
masses of all hadrons (except for pseudo-Goldstone bosons) are scaled down by
30%.
