Rozacea and demodicosis are frequent diagnoses in dermatological practice. While demodicosis is the result of infection with the Demodex parasite, the etiology of rozacea is not fully understood. Rozacea is an complex inflammatory skin disease that presents with erythema, papules, pustules and telangiectasia on the face, forehead and less often on the neck and presternal area. The etiology of the disease is multifactorial. Rozacea is a disease of the immune system, manifested by an inflammatory process that includes innate and then adaptive immune responses, which get out of control resulting in vascular, inflammatory and hypertrophic symptoms along with. Demodex folliculorum and Demodex brevis are parasites that live, in small amounts, in human pilosebaceous follicles as part of the normal adult microbiota. People are born without Demodex on their skin. Demodex controls the host's immune system, through complexed mechanisms, to ensure its own survival.