[en] Strangeness production in relativistic heavy-ion collisions has been studied by experiments NA38 and NA50 (both at the CERN/SPS), through the vector-mesons φ and ρ+ω. Results from p-W, S-S, S-Cu and S-U at 200 AGeV, and Pb-Pb at 158 AGeV are studied as a function of the dimuon transverse momentum and the collision centrality. A factor of two enhancement of the φ production is observed in sulfur- and lead-induced reactions. A multiplicity study as a function of the number of participants is shown for Pb-Pb interactions. The power-law A dependence of the inclusive cross sections is investigated. Inverse slope parameters are obtained from the dσ/dM_T spectra for the φ and the ρ+ω vector-mesons. (author)