Strange mesons in dense nuclear matter

Experimental data on the production of kaons and antikaons in heavy-ion col lisions at relativistic energies are presented and discussed with respect t o in-medium effects. The K-/K+ ratios measured in nucleus-nucleus collision s are 1-2 orders of magnitude larger than in proton-proton collisions. The azimuthal angle distributions of K+ mesons indicate a repulsive kaon-nucleo n potential. Microscopic transport calculations consistently explain both t he yields and the emission patterns of kaons and antikaons when assuming th at their properties are modified in dense nuclear matter. The K+ production excitation functions measured in light and heavy collision systems provide evidence for a soft nuclear equation-of-state.