Zn1-xMnxS epilayers have been grown on GaAs (100) substrates by hot-wall epitaxy. The structure of the epilayers was found to be zincblende over a large Mn composition range, 0 <= x <= 0.52. The relation between the Mn composition determined by energy dispersive x-ray spectrometry and the lattice constant by double crystal rocking curve was found to be consistent with Vegard's law. A broad Mn2+-related transition near 2.1 eV was observed in the low- and room-temperature photoluminescence (PL) spectra. The Mn composition dependence of PL peak energy was also investigated. (c) 2005 American Vacuum Society.