The present study was carried out to determine the incidence and density of Demodex folliculorum (Simon, 1842) and Demodex brevis Akbulutova, 1963 in patients with acne. The study included 210 patients diagnosed with acne during clinical examination, and 150 healthy controls without any facial dermatoses. In the study, samples were taken from the right cheek, left cheek, nasolabial area, and chin of the participants using the Standard Superficial Skin Biopsy technique. Samples were examined under a light microscope, and Demodex species were identified and counted. Demodex positivity (>= 5 mites) was detected in 62.4% of the patients and 16.7% of the controls in the study (p < 0.001). A total of 3325 (mean: 25.4/cm(2)) mites were isolated from Demodex-positive patients. A total of 2015 (mean: 19.2/cm(2)) mites were isolated from patients infested with D. folliculorum only, 52 (mean: 7.4/cm(2)) mites were isolated from patients infested with D. brevis only, and 1058 (mean: 65.2/cm(2)) mites were isolated from patients infested with both species. The mean density of both mites (co-infection D. folliculorum and D. brevis) was detected as 21.0, 43.5, and 117.1/cm(2) respectively, in patients with mild, moderate, and severe acne. In the controls who was Demodex positive, only D. folliculorum or co-infection with both mites were detected, not D. brevis alone. A total of 167 (mean: 6.7/cm(2)) mites were isolated from these controls. As a result, Demodex mites were found to be very common and intense in patients with acne in Erzincan, Turkey. It was also concluded that there was a positive correlation between Demodex mites and degree of acne, and that the co-infection of D. folliculorum and D. brevis aggravated the clinical picture in patients with acne. It may be helpful to consider these findings in clinical assessments of patients with acne.