Coccidioides immitis has never been reported to have been isolated from the soil of San Diego County. Case findings indicated that there were indigenous cases of coccidioidomycosis. Interviews were conducted to locate as accurately as possible sources of soil exposure. Data were gathered from 24 cases. Two persons gave information specifically indicating a certain area within an ancient Indian camp site. Soil sampling yielded thirteen isolates of the fungus. During the study of this camp-site area, it was noted that loads of soil were being removed from time to time. Since past case interviews indicated exposure to topsoil, it was decided to sample the sides of any recent excavations to see if a link could be formed to topsoil transfer of the fungus. Two samples from a fresh excavation yielded Coccidioides. Through fortuitous circumstances, the person who had removed this load of soil was discovered a few months later with an active case of coccidioidomycosis. The transported soil in this individual''s back yard was shown to harbor the fungus.