Background: For primary cutaneous lymphoma, mycosis fungoides (MF) is the most prevalent form with skin-homing T cells plus clonal proliferation of CD4. In many CTCLs, thymocyte selection associated with the HMG-box (TOX) is an uncontrolled gene, together with MF in comparison with controls. Early mycosis fungoides is difficult to diagnose, and, its distinction from inflammatory diseases is sometimes impossible. Objective: In this study, we compared the TOX vs C7 and CD4 expression as an early mycosis fungoides diagnostic markers & to assess their ability to differentiate Mycosis fungoides from benign cutaneous inflammatory diseases (BCID). Materials and methods: 60 patients who had been previously diagnosed as MF (30 cases) and BCID (30 cases). All were evaluated histopathologically using H & E and immunohistochemically staining for TOX, CD7 & CD 4. Results: There was statistically significant difference between MF and BCID with increased TOX, CD7 & CD4 expression among MF than among BCID and ability of TOX to detect all true positive cases (100.0%) compared to 83.3% for CD4 and 13.3% for CD7. TOX had the highest sensitivity (100.0%) and accuracy (88.3%) followed by CD4 with sensitivity of 88.3% and accuracy of 66.7%, (P < 0.001). Conclusion: TOX had the highest sensitivity (100.0%) & accuracy (88.3%) followed by CD4 with sensitivity of 88.3% and accuracy of 66.7%. Our results suggest that TOX is a useful marker in diagnosis of MF & differentiating it from BCID. Keywords: TOX, CD7, CD4, Mycosis fungoides (MF), Benign cutaneous inflammatory diseases (BCID), Immunohistochemistry