The development of allergic rhinitis entails a complex interaction between genetic predisposition and environmental exposure to different factors, of which the most important is the implicated allergen. There is a clear hereditary component in allergic rhinitis that has been well corroborated by segregation studies and investigations in twins. From the strictly genetic perspective, it is believed that the disease may be the result of the interaction of different genetic alterations, each of which would contribute a small defect. In recent years, considerable attention has focused on the genes that may be implicated in allergic rhinitis. A number of genomic searches have been made, yielding different chromosomal associations--the most repeated being those involving chromosomes 2, 3, 4 and 9. Single-nucleotide polymorphism studies involving genes encoding for molecules implicated in the pathogenesis of allergic rhinitis have also been made. Such molecules comprise chemokines and their receptors, interleukins and their receptors, eosinophil peroxidase and leukotrienes, among others.