Studies using rats that were naturally infested with Syphacia muris and kept in forced-air, individually ventilated cages showed that ivermectin given orally at a dose of 2 mg/kg for three treatments at 7- or 9-day intervals was eradicative. Paired ivermectin treatments given at 7- or 9-day intervals were ineffective in eliminating parasitism. Pinworm eggs persisted on the perianal region of rats for up to 17 days and eggs were also present in soiled contact bedding within cages and on surfaces within the animal room. Anal tapes as a diagnostic test had 88% sensitivity in detecting pinworms.