Thermal hadron production in high-energy collisions

It is shown that hadron abundances in high-energy e(+)e(-),pp and p p (p) over bar collisions, calculated by assuming that particles originate in hadron-gas fireballs at thermal and partial chemical equilibrium, are in very good agreement with the data. The freeze-out temperature of the hadron-gas fireballs turns out to be nearly constant over a large centre-of-mass energy range and not dependent on the initial colliding system. The only deviation from chemical equilibrium resides in the incomplete strangeness phase-space saturation. Preliminary results of an analysis of hadron abundances in S + S and S + Ag heavy-ion;collisions are presented.