The objectives of this study were to investigate antimicrobial properties of sodium metasilicate (SMS) on fresh boneless and skinless commercial broiler chicken breast fillets, and to ascertain effects of the treatments on sensory, chemical, and physical characteristics of the meat. Fillets were divided into 5 groups, weighed, treated with 0, 1, 2, 3, or 4% SMS marinades, vacuum tumbled at 172.32 kPa for 20 min, reweighed, packaged in styrofoam trays, stored at 4°C for 9 d, and analyzed at 0, 1, 3, 5, 6, 7, and 9 d for marination yield (d 0 only), pH, total psychrotrophic counts, water-holding capacity, purge loss, cooking yield, and objective texture, color, and sensory characteristics. Marination yield and water-holding capacity were similar (P > 0.05) among all SMS treatments and increased by 3 to 4% compared with that in control fillets. Fillets treated with at least 3% SMS had higher (P < 0.05) pH and cooking yields and lower (P < 0.05) purge loss (on d 9) compared with control fillets. The 3 and 4% SMS treatments retarded growth of psychrotrophic organisms for 1 additional day compared with control, 1, and 2% SMS-treated fillets. Color and texture measurements and sensory characteristics of the fillets were not adversely affected by the SMS treatments. The data in this study revealed that at least 3% SMS was necessary to retard growth of spoilage bacteria compared with untreated samples and samples treated with the USDA maximum allowable level of 2% SMS in poultry marinades.