During the fall of 2005, a study was conducted at Priest River Experimental Forest (PREF) in northern Idaho to investigate the economics of mastication used to treat activity and standing live fuels. In this study, a rotary head masticator was used to crush and chop activity fuels within harvest units on 37.07 acres. Production averaged 0.57 acres/hour (range 0.21-0.89 ac/hr). Costs average $530 per acre (range $335-$1395 per acre). Additionally, eleven fireline segments totaling 2326 feet were constructed through activity fuels using the same mastication machine. On average, 18 ft of fuelbreak was created through mastication (range 16-23 feet) combined with 4 ft of fireline (range 3-5 feet) with 100 percent mineral soil exposure constructed down the center of the trail. Total debris (including activity fuels) ranged from 26-61 tons per acre with production averaging 6.9 feet per minute (range 3.1-9.1 feet). This manuscript, concentrates on cost-analysis concerning mastication and it has shown that stand and site characteristics such as slope. residual tree density. and total acreage can significantly affect the time required to treat these areas. This research as it progresses will provide data on cost-benefit analyses comparing mastication, prescribed fire, and grapple piling/burning site preparation and fuel treatment alternatives.