Oral rabies vaccination (ORV) baiting programs for control of raccoon (Procyorl lotor) rabies in the USA have been conducted or are in progress in eight states east of the Mississippi River. However, data specific to the relationship between raccoon population density and the minimum density of baits necessary to significantly elevate rabies im~nunity are few. We used the 22-km2 US National Aeror~autics and Space Administration Plum Brook Station (PBS) in Erie County, Ohio, USA, to evaluate the period of exposure for placebo vaccine baits placed at a density of 75 baits/km2 relative to raccoon population density. Our objectives were to 1) estimate raccoon population density within the fragmented forest, old-field, and industrial landscape at PBS; and 2) quantify the time that placebo, Merial HABORAL V-RG" vaccine baits were available to raccoons. Froin August through November 2002 we surveyed raccoon use of PBS along 19.3 km of paved-road transects by using a forward-looking infrared camera rnol~r~ted inside a vehicle. We used Distance 3.5 software to calc~~late a probaljility of detection function by whit11 we estimated raccoon pop~ilation density from transect data. Estimated population density on PBS decreased from August (33.4 raccoons/km2) through November (13.6 raccoons/krn2), yielding a monthly rnean of 24.5 raccoons/km2. We also quantified exposure time for ORV baits placed by hand on five 1-km2 grids on PBS from September through October. An average 82.7% (SD=4.6) of baits were removed within 1 wk of placement. Given raccoon population density, estimates of bait removal and sachet condition, and assllming 22.9% nontarget take, the baiting density of 75/ km' yielded an average of 3.3 baits consurned per raccoon anti the sachet perforated.