Objective: To evaluate attachment and proliferation of human gingival fibroblasts (HGFs), human periodontal ligament fibroblasts (HPDLFs) and human osteoblasts (HOBs) on diseased root surfaces of human teeth demineralised with EDTA and subsequently treated with freshly prepared platelet-rich plasma (PRP) or platelet-poor plasma (PPP) from human blood. Methods: HGFs, HPDLFs and HOBs were grown from tissue explants. Human whole blood from healthy subjects was collected to prepare PRP and PPP. The root surfaces of periodontitis- affected teeth were scaled, sectioned, and demineralised with EDTA and treated with PPP or PRP or none. The control group was neither demineralised nor treated with PPP or PRP. The cementum surfaces of root slices were cultured with HGFs, HPDLFs or HOBs for 24 or 48 h. Attachment and proliferation of cells were evaluated using cell count, scanning electron microscopy and MTT assay. Results: The root surfaces of the control group demonstrated the least number of attached cells. Demineralisation alone or combined with PRP or PPP increased cell attachment and proliferation. Electron microscopic evaluation further confirmed that both PRP and PPP significantly enhanced cell attachment to the diseased root surfaces. Conclusion: Pretreatment of diseased human root surfaces with EDTA, PRP or PPP enhances the attachment and proliferation of HGFs, HPDLFs and HOBs to the diseased root surface. Keywords: periodontal cells, attachment, platelet-rich plasma, platelet-poor plasma, demineralisation