Seborrheic dermatitis is a chronic relapsing erythematous scaly skin disease, the prevalence of which is around 1 to 3% of the general population in the United States. It has two incidence peaks, the first in the first three months of life and the second beginning at puberty and reaching its apex at 40 to 60 years of age. The prevalence of seborrheic dermatitis is higher in HIV-positive individuals and the condition tends to be more intense and refractory to treatment in these patients. Neurological disorders and other chronic diseases are also associated with the onset of seborrheic dermatitis. The currently accepted theory on the pathogenesis of this disease advocates that yeast of Malassezia spp., present on the skin surface of susceptible individuals, leads to a non-immunogenic irritation due to the production of unsaturated fatty acids deposited on the skin surface. This article provides a review of the literature on seborrheic dermatitis, focusing on immunogenetics, the clinical forms of the disease and its treatment.