Presence of human immunodeficiency virus (HIV) within noninflamed human dental pulps was documented by polymerase chain reaction assays in 11 of 12 pulps from HIV-seropositive patients. The purpose of the present study was to determine the cellular location of HIV in vivo within these tissues by means of in situ hybridization. Results of the in situ hybridization indicated HIV within fibroblasts of the pulp. These results are especially relevant because fibroblasts lack the CD4 receptor thought necessary for in vivo infection with HIV. These results suggest the fibroblast as a possible reservoir for HIV in the body.