BACKGROUND Demodex may cause chronic and refractory blepharitis with associated ocular surface problems, and its diagnosis and treatment can be quite challenging. In this study, our aim was to assess the efficacy of tea tree oil in Demodex treatment on caucasian patients in an industrialized region of Turkey, and to develop a systematic scoring system for extremely accurate diagnosis in the absence of advanced facilities. MATERIAL AND METHODS Charts of 412 patients with blepharitis were reviewed. A group of 39 out of 412 cases were identified as chronic and treatment-refractory, and therefore were enrolled in this study. Eyelashes from each of the lower and upper eyelids of both eyes were evaluated at ×40 and ×100 magnification using light microscopy. Treatment was started with 4% tea tree oil eyelid gel and 10% eyelash shampoo. Symptoms and findings were scored according to the most common complaints. RESULTS The mean age of the patients was 54.1±15.4 years. Seventeen (43.5%) patients were male and 22 (56.5%) patients were female. In 30 out of the 39 patients (76.9%) D. folliculorum was detected. Symptoms disappeared in 25 patients. The mean score of patients who were Demodex-negative was 2.7±1.0, and the mean score of patients who were Demodex-positive was 3.8±1.6 (p=0.047). Ninety-four percent of those with a score of 4 and over were found to be Demodex-positive (p=0.025). CONCLUSIONS Treatment with tea tree oil can be successful. If there is no facility to identify Demodex under light microscopy, we recommend starting treatment for patients who have scores of 4 and over using the scoring chart developed in this study.