Abstract: Despite their highly detrimental effect on the environment, humans and animals, andan evolution of resistence to them which was observed in the EU as far back as in the 1970s,anticoagulant rodenticides have continued to be the most widely represented means of controllingpopulations of commensal rodents. In Serbia, potential rodent resistance to those compounds hasnot yet been thoroughly researched. In keeping with global trends of introducing moreenvironment-friendly products, a rodenticide based on sodium selenite has been used in Serbia tocontrol commensal rodents. The mechanism of activity of sodium selenite is based on anexchange of SH-S-S groups of functional enzymes. Experiments were conducted at a flour millfacility in Serbia (GPS.: 44°45’N, 20°44’E), following a standard EPPO procedure, to test theefficacy of baits containing 0.1% sodium selenite against Mus musculus in facilities for wheatmilling and flour packaging and storing, and against Rattus norvegicus around the mill, in wheatstorage rooms and outbuildings. Baits were laid in boxes, at 1-3m intervals and in 30g portionsfor Mus musculus, and 150g portions appropriately positioned for Rattus norvegicus.Additionally, 100g baits were laid in active holes of Rattus norvegicus found in the mill’svicinity. The numbers of commensal rodents were evaluated based on the highest and lowestdaily bait take over a 10-day experimental period, divided by the daily required amount offeeding, and using a census method before and after treatment. The results showed that theefficacy of sodium selenite baits, calculated from the ratio of required daily diet and daily baittake, and by census method, was 89.38% and 81.48% for Mus musculus, and 82.12% and 78.57%for Rattus norvegicus.