OBJECTIVE To evaluate the effects of vaporized hydrogen peroxide (VHP) sterilization on the in vitro antimicrobial efficacy of meropenem-impregnated polymethyl methacrylate (M-PMMA) beads. SAMPLE 6-mm-diameter polymethyl methacrylate beads that were or were not impregnated with meropenem. PROCEDURES Meropenem-free polymethyl methacrylate and M-PMMA beads were sterilized by use of an autoclave or VHP or remained unsterilized. To determine the antimicrobial efficacy of each bead-sterilization combination (treatment), Mueller-Hinton agar plates were inoculated with 1 of 6 common equine pathogens, and 1 bead from each treatment was applied to a sixth of each plate. The zone of bacterial inhibition for each treatment was measured after 24 hours. To estimate the duration of antimicrobial elution into a solid or liquid medium, 1 bead from each treatment was transferred every 24 hours to a new Staphylococcus aureus–inoculated agar plate or a tube with PBS solution, and an aliquot of the eluent from each tube was then applied to a paper disc on an S aureus–inoculated agar plate. All agar plates were incubated for 24 hours, and the zone of bacterial inhibition was measured for each treatment. RESULTS In vitro antimicrobial efficacy of M-PMMA beads was retained following VHP sterilization. The duration of antimicrobial elution in solid and liquid media did not differ significantly between unsterilized and VHP-sterilized M-PMMA beads. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that M-PMMA beads retained in vitro antimicrobial activity and eluted the drug for up to 2 weeks after VHP sterilization.