Aims: To evaluate the field inactivation of Bacillus anthracis Sterne spores with methyl bromide (MB) using commercial fumigation techniques. Methods and Results: Eighty-seven wood and 87 glass coupons each containing ca. 1 x 10(6) B. anthracis Sterne spores, were placed in 22 locations inside a 1444 m(3) conference building. Four additional 12-coupon sets (six wood, six glass) were removed from the building at 16, 24, 32 and 40 h during fumigation. The building was sealed under two tarpaulins and fumigated with MB at >= 225 g m(-3) mean concentration for 48 h at 28 degrees C and 83% RH. All B. anthracis spores fumigated for more than 16 h were inactivated. A single wood coupon from the 16-h set yielded ca. 2 x 10(3) CFU. No damage to the building or its contents was observed. Conclusions: MB fumigation is a rapid, economical and effective whole-structure decontamination method for B. anthracis spores. Significance and Impact of the Study: MB fumigation offers a method of whole-structure B. anthracis decontamination without removal of materials, damage to sensitive electronics, costly indoor retrofitting.