Background: Steroid rosacea, perioral dermatitis, fungal infections, demodex dermatitis are side effects frequently observed in acne patients after application of corticosteroids for prolonged periods. Increased number of Demode fo//ieu/orum has also been observed in perioral dermatitis and rosacea patients. Ojectives: To confirm the skin flora contamination and relative factors in acne patients using topical corticosteroids. Methods: Crosssectional descriptive study. Results: According to the observation of 411 acne patients using corticosteroids seen at cantho hospital of dermato- venereology, the authors found that: The discovery of pathogenic parasites rising up on skin: Demodex (18,5 percent), fungi (12,9 percent), the combination of demodex and fungi (11,2 percent). Demodex was found in pustular acne 29,9 percent, perioral dermatitis 35,5 percent.Conclusion: Demodexand fungi are the pathogenic parasites that have been observed in acne patients using topical corticosteroids.