The purpose of this study was to determine the discriminative factors between rheumatoid arthritis (RA) patients with and without major depression (MD). We assessed subjective sleep quality, pain, and cell-mediated immune functions in RA patients with (n = 20) and without (n = 20) MD by using Pittsburgh Sleep Quality Index (PSQI), visual analogue scale (VAS), and fluorescein isothiocyanat (FITC) labeled CD3, CD4, CD8, CDI9, CD45, CD56, and HLADR T monoclonal antibodies by flow cytometry. We found that the RA patients with MD had significantly higher pain level, poorer sleep equality, higher HDRS points, and higher HLADR T cell level than those without MD; and that these variables are discriminant factors between patient groups. These findings suggest that the RA patients with MD may be differentiated from those without MD by using VAS, PSQI, and HLADR levels; that these variables correctly classify the depressed and non depressed groups up to an accuracy level of 96.8%.