Stereotaxic inoculation was used to examine the role of scrapie agent strain, inoculum, and injection site on the brain regional distribution ofthe prion protein, PrP27-30. Neither the type of inoculum nor the injection site influenced the distribution of PrP27-30 in brains of mice. Among the parameters examined, only the strain of agent affected the pattern of distribution and the yield of PrP27-30. Although mice injected into the cerebellum had the shortest incubation period, the cerebellum gave the lowest yield of the PrP27-30 among the seven brain regions examined. The positive correlation between PrP27-30 regional distribution and lesion profile (degree of vacuolation) reinforces the role of the Prpsc protein in scrapie pathogenesis.