Chronic blepharitis is an ocular disease frequently encountered by ophthalmologists. Demodex mites can play a role in the pathogenesis of blepharitis along with bacterial agents, especially in treatment-resistant cases or recurrent cases after treatment. This study was performed to determine the prevalence and load of Demodex folliculorum (Simon) and Demodex brevis Akbulutova in chronic blepharitis patients and to assess the relationship between the prevalence and load of Demodex species and ocular symptoms. The study included 365 patients diagnosed with chronic blepharitis in clinical examination, and 175 controls without any chronic or ocular disease. In the study, two eyelashes were sampled from the lower and upper lids of the right and left eyes (a total of eight samples) of the participants. Eyelash samples were examined under a light microscope, and Demodex species were identified and counted. Demodex were detected in 79.2% (95% CI: 75-83%) of patients and 31.4% (95% CI: 24-38%) of controls in this study. D. folliculorum alone (mean: 4.96; min: 1; max: 17; P < 0.001) was detected in 72.3% of patients, in 0.7% D. brevis alone (mean: 1.00, P > 0.05), and in 27% both D. folliculorum and D. brevis (mean: 21.65; min: 2; max: 79; P < 0.001). In Demodex positive controls, only D. folliculorum (mean: 2.38; min: 1; max: 6) was detected while there was no D. brevis. Nevertheless, mean ocular symptom scores were significantly higher in Demodex positive patients than in Demodex negative patients (P < 0.001). Itching, foreign body sensation, and redness were the most common complaints in Demodex positive patients. As a result, Demodex mites were high in numbers in patients with chronic blepharitis in Erzincan. There was a positive correlation between Demodex mites and chronic blepharitis and ocular symptoms. It may be helpful to consider these findings in clinical assessment of blepharitis patients.