Various theories on the causes of blushing are reviewed in this paper. Darwin held that interest in personal appearance and concern about the opinion of others are important causes of blushing. Other theories emphasize exhibitionism, masochism, scopophilia, sadism, urethral erotism, or castration fear as contributing factors. Karch concludes that, in general, an ego ideal goal which is related to physical appearance is not attained and the blusher feels shamed and depreciated.