BACKGROUND Acne vulgaris is a chronic inflammatory disease with multifactorial etiology. Studies on the pathogenesis of acne are still important. Recently, various studies have been conducted on the significance of genetics in the pathogenesis of acne. Blood group is transferred genetically and could affect the development, progress, and severity of certain diseases. OBJECTIVE In the current study, the correlation between the severity of acne vulgaris and ABO blood groups was investigated. METHODS A total of 380 patients (263 mild and 117 severe acne vulgaris patients) and 1000 healthy individuals were included in the study. Severity of acne vulgaris patients and healthy controls was determined based on the blood group and Rh factor data obtained retrospectively from the patient files in the hospital automation system. RESULTS In the study, the rate of females was significantly higher in the acne vulgaris group (X2 :154.908; p:0.000). The mean age of the patient was significantly lower when compared to the controls (t:37.127; p:0.0001). The mean age of the patients with severe acne was significantly lower when compared to those with mild acne. When compared to the control group, the incidence of severe acne was higher in those A blood type when compared to the patients with mild acne, while the incidence of mild acne was higher in other blood groups when compared to the control (X2 :17.756; p:0.007). No significant difference was determined between the Rh blood groups of the patients with mild, severe acne and the control group (X2 :0.812; p:0.666). CONCLUSIONS The results revealed a significant correlation between acne severity and ABO blood groups. Future studies that would be conducted with larger samples in different centers could confirm the current study findings.