Background: acne vulgaris is chronic inflammatory dermatosis of the pilosebaceous units which is characterized by open and/or closed comedones (blackheads and whiteheads) and inflammatory lesions including papules, pustules, or nodules, in some cases, is accompanied by scarring. Acne is multifactorial disease including increased sebum production, hypercornification of pilosebaceous duct, an abnormality of microbial flora especially colonization of the duct with propionibacterium acne and the production of inflammation. P.acne has been implicated in the pathogenesis of acne for more than 100 years.  Objective: the present work was done to determine bacteria involved in acne vulgaris among Egyptian acne patients. Patients and Methods: this study was conducted on one hundred patients with inflammatory acne vulgaris recruited from the Dermatology outpatient clinic of Al-Hussien hospital. Results: in this study, S.epidermidis was higher in normal skin than in acne lesion. But P.acne was higher in acne lesion than in normal skin with significant statistical difference. There was a significant relation between type of organisms isolated and severity of acne lesions in both aerobic and anaerobic state. There was a significant relation between positive acne family history and liability for post acne scar. Even though there was no significant relation between hermonal therapy and severity of acne lesions. We noticed that the majority of female patients with POP history had moderate acne lesions. In this study, the high percentage of S.epidermidis was observed in moderate acne lesion and in normal skin in aeorobic state but high percentage of P.acne was found in moderate acne lesions in anaerobic state. However, P.acne can not be solely held responsible for the initiation of inflammation in inflamed acne lesions or for the variation in its severity. Conclusion: the high percentage of no growth result in this study directs us that the antibiotic treatments are not the most useful treatment for acne and there are other effective methods for treatment whether topical as retenoids or ablative as Lasers. Patient with family history of acne lesion especially first relative (mother) we must keep in mind that they are more susceptible for post acne scar so we should start with the perfect treatment as early as possible to prevent the post acne sequels.