Background: Acne is the most common skin disease of adolescents and young adults. It is a complex skin disorder that distresses many patients because of its chronicity. Acne vulgaris is a common inammatory disorder of the pilosebaceous unit. Vitamin D regulates the immune system and the proliferation and differentiation of keratinocytes and sebocytes. Vitamin D deciency may facilitate the pathogenesis of acne Methods: This research is an observational study with cross-sectional data collection methods to determine Vitamin D levels as a predictor of acne severity in patients. The study was conducted in a laboratory at the Royal Prima Medan General Hospital, starting in July 2022. Sampling was carried out consecutively for all affordable populations who met the study criteria, namely 30 patients suffering from acne. Results and Discussion: The cut Point value of 23.57 pg/mL for vitamin D levels to predict the severity of acne vulgaris, a sensitivity value of 87.5%, a specicity of 78.6%, a positive predictive value of 87.5% and a negative predictive value are obtained. of 84.6%, the accuracy of vitamin D levels to predict the severity of acne vulgaris was 83.3%. Conclusions and suggestions: Our study shows that vitamin D levels can be used to predict the severity of acne vulgaris. The more severe the severity of the acne, the lower the Vitamin D in the blood