Background: Primary cutaneous lymphoma (PCL) with clonal proliferation of atypical CD4+ skin-homing T lymphocyte cells is called Mycosis Fungoides (MF). TOX staining is observed in subtypes of PCL, as MF & Sézary Syndrome (SS) in comparison to controls. Early MF is difficult to diagnose, & its distinction from inflammatory diseases may be impossible. Objective: This study aimed to evaluate the expression of the TOX versus CD3 as a diagnostic marker for early MF. Patients and methods: retrospective-cross sectional study includes 30 MF and 30 benign cutaneous inflammatory diseases (BCID) cases. All were evaluated using H & E and immunohistochemical staining for TOX & CD3. Results: There was statistically significant increase of TOX & CD3 expression in MF than BCID & ability of TOX to detect all true positive cases (100.0%) compared to (76.7%) for CD3, (P < 0.001). Conclusion: TOX had the highest sensitivity (100.0%) & accuracy (88.3%). TOX is useful marker in the diagnosis of early MF & differentiating it from BCID.