Permethrin-impregnated cotton was distributed to reduce abundance of immature Ixodes dammini Spielman, Clifford, Piesman & Corwin feeding upon white-footed mice (Peromyscus leucopus) and questing on vegetation at a private resort site (The Crane Reservation of The Trustees of Reservations in Ipswich, Mass.) located in coastal New England. This test constituted the first independent evaluation of the efficacy of this commercial product (Damminix). Over a 3-yr period, 2,000 applicator tubes containing treated cotton were distributed over the 7.3-ha site in 5 regularly scheduled applications. Mice removed treated fiber from the tubes and transported it to their nests. Within 3 wk of the first application, virtually all mice in the treated site were rendered free of ectoparasites. After the first season of application, no nymphal host-seeking I. dammini could be found on vegetation. Visitor and employee complaints about deer tick bites or ticks found on skin and clothing had been attributed to the site before treatment, but not thereafter. We confirmed the efficacy of Damminix for reduction of the abundance of vector ticks and thereby contributed to the protection of humans against Lyme disease at this site.