Background: Interleukin-31 (IL-31) is a cytokine that is commonly reported with inflammatory skin diseases and pruritus. It was positively correlated with disease activity in atopic dermatitis and primary cutaneous lymphoma. Epidermal keratinocytes express the subunits forming the receptor for this cytokine and thus may play a role in the inflammatory status of different dermatological diseases in which IL-31 might play a role. Objective: This study aimed to evaluate the role of IL-31 and CRP in inflammatory acne vulgaris patients, for the understanding of a distressing disease and thus better therapies relevant for each case. Patients and methods: This case-control study included 40 diagnosed patients with acne vulgaris and 40 healthy controls who were comparable in age and sex to cases. They were randomly chosen from the outpatient clinic of Mansoura University Hospital's Dermatology Department. Results: There was a statistically significantly higher median IL-31 among the studied cases than in the control group (P=0.013). There was a statistically significant higher median CRP among studied cases than in the control group (P=0.035). Detection of CRP & IL-31 levels can be used as a reliable indicator in differentiating studied cases with the best-detected cut-off point being 0.650 &911 respectively yielding a sensitivity of 65 & 67.5 and specificity of 52.5% &50%, respectively. Conclusion: This work suggested a pathogenic role of IL-31 in acne patients being related to the severity and inflammation, opening gates for a better understanding of the pathogenesis of common dermatological disease and thus better treatment results.Serum levels of CRP are elevated in acne vulgaris and are correlated with the disease severity.