AIM: To investigate clinical presentation, classification,diagnosis, pathogenesis, complication and treatment of blepharitis.METHODS: In this study, 300 patients referred to general eye clinic have been chosen with diagnosis of blepharitis by Haag-streit slit-lamp examination. A questionnaire was filled in for patient with blepharitis. Then, the treatment of out-patient cases based on the causes of the condition was started.Patients were followed up and evaluated with respect to the results and complications of the treatment.RESULTS: The most common form of lesion in seborrheic dermatitis was squamous (62.5%) but ulcerative lesions was the most common in infectious and mixed types (P ＜0.001).Also, Seborrheic blepharitis mostly had chronic clinical course but infectious type commonly was acute (P ＜0.001). A significant difference was found between the cause of blepharitis and incidence of complications including hordeolum, chalazia, epithelial keratitis, conjunctivitis, dry eye (P ＜0.05). Moreover, There was a significant difference between clinical course of disease and complications such as dry eye and epithelial keratitis (P ＜0.05). There was a close relationship between the underlying diseases including seborrheic dermatitis, atopic dermatitis, diabetes mellitus,allergy, acne rosacea and the cause of blepharitis(P ＜0.05).CONCLUSION: The blepharitis is one of the most common problems in general ophthalmology and needs attention to prevent the complications.