Perioral dermatitis has been ascribed to the use of oral contraceptives, cosmetics, toothpastes or to an infection with Candida or Fusobacteria, etc. However, seborrheic diathesis, together with the use of potent topical steroids, appeared to be the main cause of the affection. This was confirmed with the help of a number of observations in the clinic and by inference from data regarding the geographical spread of the potent steroids.