A study was conducted to assess the effect of UV 254 on the concentration and viability of PRRSV on surfaces and materials commonly encountered on swine farms. A standard quantity (5×10 6TCID 50, total dose) of a PRRSV modified live vaccine virus was inoculated onto 2 matched sets of surfaces/materials including wood, plastic, latex, rubber, styrofoam, metal, leather, cloth, concrete, cardboard, glass and paper. One set was exposed to UV 254 radiation (treatments) and the other to incandescent light (controls) for a 24h period. During this time, treatments and controls were swabbed at 10min intervals from 0 to 60min post-inoculation (PI) and again at 24h PI. The quantity of PRRSV RNA on each item at each sampling time was calculated by RT-PCR and the presence of viable PRRSV in each sample was determined by swine bioassay. A significant reduction (p<0.0001) in the quantity of PRRSV RNA was demonstrated at 24h PI independent of treatment. In addition, a significant reduction (p=0.012) in the number of UV 254-treated surfaces which harbored viable virus was observed at 60min (0/12 positive) when compared to control surfaces (5/12 positive). In addition, all UV 254 treated samples collected between 10 and 50min PI were bioassay negative. These results suggest that UV 254 is an effective means to inactivate PRRSV on commonly encountered farm surfaces and materials and inactivation can be accomplished following 10min of exposure.