The purpose of this study was to assess connective tissue and epithelial responses to cementum (from normal human root surfaces covered by periodontal ligament) after surface demineralization with citric acid. Each rectangular specimen had a face of cementum and an opposite surface composed of pulpal dentin. One half of the specimens were treated with citric acid (experimental group), while the remainder served as untreated control specimens. Specimens were implanted vertically into incisional wounds on the dorsal surface of rats with one end of the implant protruding through the skin. Four specimens in each group were available for examination 1, 3, 5, and 10 days after implantation. Histologic and histometric analyses of the implants included counts of adhering cells, evaluation of attached connective tissue fiber density and diameter, and assessment of epithelial migration. At day 1, a distinct lighter staining zone was present on the surface of both cementum and dentin in the experimental group which corresponded to a zone of surface demineralization produced by the acid treatment. Histometric comparisons between experimental and control groups at 10 days showed a greater number of cells attached to demineralized cementum surfaces. Also, a connective tissue fiber attachment system had developed on these experimental surfaces, but which differed morphologically from periodontal ligament fiber attachment to normal cementum. It was concluded that citric acid treatment can surface demineralize cementum from normal roots, and that the surface demineralization of this cementum facilitated a cell and fiber attachment to the cementum surface.