Objective: To report on three cases of posterior scleritis presenting as orbital cellulitis. Case Report: The authors retrospectively reviewed the medical records of three patients who were diagnosed as posterior scleritis but initially presented as orbital cellulitis. All patients were young males who presented with pain, unilateral proptosis, eyelid swelling with redness, and limitation of ocular movement. Initially, the diagnosis of orbital cellulitis was suspected and patients had been treated with systemic antibiotics but with no clinical improvement. Systemic work-up for infections and autoimmune diseases were negative. The orbital computed tomography (CT) scans showed severe posterior eyewall thickening with associated soft tissue edema. Ultrasonography showed a typical T-sign, compatible with posterior scleritis. Specific cause of scleritis or an association with systemic disease was not established. Systemic corticosteroids (1 mg per kg per day) were administered, and all patients improved within several days. Conclusion: Posterior scleritis is a rare and severe ocular inflammatory disorder that can mimic orbital cellulitis. Early detection and prompt treatment is crucial. Keywords: Posterior scleritis, Orbital cellulitis, Non-specific orbital inflammation, Orbital computed tomography scan, T-sign ultrasonography